PA-CF, PPA-CF or PEEK-CF?

From left to right: components made of PA-CF, PPA-CF, and PEEK-CF, Malping GmbH

Short answer: PA-CF covers the majority of functional components used at temperatures up to approximately 100 °C and is the most cost-effective of the three variants. PPA-CF can be used continuously at higher temperatures up to around 180 °C, making it the material of choice for engine compartments and drive systems. PEEK-CF starts above this and extends to a continuous operating temperature of 260 °C, in addition to contact with aggressive chemicals and components subjected to tribological stress. The choice of material rarely depends on tensile strength, but rather on temperature, medium, and budget.

PA-CF, PPA-CF or PEEK-CF in numbers

All values are taken from our material data sheets, measured on printed test specimens from the respective filament manufacturers.

Key figure	PA6-CF15	PPA-CF25	PEEK-CF30
Fiber content	15%	25%	30%
Density (g/cm³)	1.25	1.23	1.41
Tensile strength XY (MPa)	110 (0°)	121	169
E-modulus of train XY (MPa)	10,500 (0°)	10,220	17,310
Elongation at break XY (%)	0.98	1.6	3
Glass transition temperature Tg (°C)	68	80	143
HDT 1.8 MPa (°C)	120	126 (tempered)	n/a
HDT 0.45 MPa (°C)	n/a	199 (tempered)	n/a
Maximum continuous operating temperature (°C)	approximately 100	approximately 180	260
Water absorption (%)	> 0.3 (24 h)	1.09 (ISO 62)	0.50 (ISO 62)
Test standard train	ISO 527	ASTM D638	ISO 527

A preliminary note to put part of the table into context: The tensile strength values for PPA are determined according to ASTM D638, while the values for PA and PEEK are based on ISO 527. These two standards specify different specimen geometries and testing speeds. Therefore, a comparison down to the last percentage point is not permissible. For material selection, considering the order of magnitude is sufficient; for design purposes, you should use the value specified in the standard according to which the calculation is performed.

The second point is the more interesting one: At room temperature, PA6-CF15, with a Young's modulus of 10,500 MPa, is practically as stiff as PPA-CF25 with 10,220 MPa. If stiffness alone is considered, the use of the more expensive material cannot be justified. The crucial difference lies in its behavior at temperatures above 80 °C.

PA-CF: the all-rounder for everything up to 100 °C

PA6-CF15 and PA12-CF15 are the workhorses of functional FFF printing. They are characterized by high stiffness, good resistance to oil, grease, and fuel, minimal warpage in large-format components, and moderate material costs. For fixtures, gauges, holders, housings, and functional prototypes, they are the right choice in nine out of ten cases.

The limiting factor is thermal resistance. The glass transition temperature of PA6-CF15 is 68 °C. Above this temperature, the matrix softens. While the fibers continue to provide structural stability, the stiffness of the component measurably decreases. The heat deflection temperature of 120 °C at 1.8 MPa is a standard value under defined bending stress and does not imply suitability for continuous use at 120 °C. We consider the practical upper limit to be around 100 °C, and below that for significant mechanical loads.

Within this category, PA6-CF15 is recommended for applications requiring maximum stiffness, as well as for planar components subjected to in-plane loading. PA12-CF15 is suitable for lightweight structures with a density of 1.07 g/cm³, for tougher components, clips and snap connections, and for all applications where moisture absorption affects dimensional stability. An important note regarding PA12-CF15: Our data is based on the manufacturer's reference values and not on printed test specimens. The stated HDT values are very close to the melting point and are not to be expected in a printed component.

Furthermore, a note on anisotropy. This affects all three materials, but is particularly evident here: PA6-CF15 reaches 110 MPa in the path direction (0°) and 70 MPa perpendicular to it. In this case, the path orientation has a greater influence than the choice of material.

PPA-CF: the automotive class between 100 and 180 °C

PPA, a semi-aromatic polyphthalamide, bridges the performance gap between PA-CF and materials such as PPS and PEEK. Typical automotive applications include engine compartment components, charge air and cooling systems, sensor and connector housings, motorsport components, and test fixtures for temperature-controlled environments.

PPA-CF25 exhibits a tensile strength of 121 MPa, a modulus of elasticity of 10,220 MPa, and a flexural strength of 185 MPa. The filament has a core-sheath structure: the fibers are located in the core, while the sheath consists of fiber-free PPA. Its water absorption according to ISO 62 is 1.09%, a value significantly lower than that of an aliphatic PA 6 until saturation. This is a crucial advantage for manufacturing dimensionally accurate components for use in humid environments.

A crucial detail regarding PPA is not found in the main table, but in a footnote: The specified properties apply to tempered components. Untempered, the heat deflection temperature of PPA-CF25 is 97 °C (test stress 0.45 MPa), while tempered this value increases to 199 °C. This corresponds to a difference of more than 100 K for the same component. Those who use untempered PPA have paid the additional cost compared to PA-CF without gaining the high-temperature material. Conversely, tempering comes at the expense of toughness: The Charpy impact strength drops from 13.1 to 7.3 kJ/m², a decrease of more than 40%.

The temperature rating is equally important. The value of 199 °C applies to a test voltage of 0.45 MPa, while the datasheet specifies a value of 126 °C for 1.8 MPa. Both values are correct, but the value corresponding to the specific temperature rating is decisive for the design. If electrical insulation or a light component color is required, PPA-GF15 from the same product family is the more suitable choice, as it has a lower anisotropy of 1.41:1. For true ESD protection with proven surface resistance, we offer PA612-ESD, although this material exhibits the temperature limitations typical of PA materials.

PEEK-CF: High-end, when the requirement demands it

PEEK-CF30 exhibits a tensile strength of 169 MPa and a modulus of elasticity of 17,310 MPa. This corresponds to a stiffness approximately 65 to 70% higher than that of the other two materials. The glass transition temperature is 143 °C, the continuous service temperature is 260 °C, and the melting point is 343 °C. Furthermore, the material offers superior chemical resistance compared to PA and PPA, tribologically optimized properties for sliding and wear applications, and semi-insulating electrical properties, a beneficial characteristic in ESD-sensitive environments. Typical applications include aerospace, defense, the chemical and process industries, and test bench construction.

Two limitations must be considered. First, the anisotropy: The values in the XY plane are 169 MPa and 17,310 MPa, while in the Z direction they are only 71 MPa and 4,165 MPa. The fibers reinforce the web, not the interface between the layers. In PEEK-CF, the drop in stiffness perpendicular to the web is most pronounced, by a factor of four. This makes component orientation a design aspect and not merely a manufacturing issue.

Secondly, consider this option: If biocompatibility, compliance for food contact according to Regulation EC 1935/2004, or maximum toughness are required, then unreinforced PEEK 450 natural with an elongation at break of 19% is not the right material. For applications requiring increased stiffness with electrical insulation, GF-PEEK is the appropriate choice. Within the PEEK product family, carbon fiber is a choice based on stiffness and tribology, not automatically the best PEEK variant.

Regarding the budget: PEEK is significantly more expensive than PPA, while PPA is in turn significantly more expensive than PA-CF. For larger components and small production runs, we reduce costs by using the FGF (Fused Granulate Fabrication) process on our ExAM-510 system. Granules are considerably more cost-effective than filament, and the build volume reaches up to approximately 510 × 510 × 410 mm. We manufacture PA-CF and PPA-CF components using the FFF process with dimensions of up to 350 × 350 × 450 mm.

Three questions that decode every datasheet number

1. Tempered or untempered? For PPA, this determines approximately 100 K of heat resistance; for PEEK, it determines crystallinity, strength, and dimensional stability during operation.

2. At what load level? HDT at 0.45 MPa and HDT at 1.8 MPa often differ by 70 K. The decisive factor is the actual temperature level present in the component.

3. In which direction? XY values are path values. The layer boundary in Z carries significantly less tensile strength in fiber-reinforced materials, only around 40% in PEEK-CF.

   
   

Decision based on five questions

Ask	PA-CF	PPA-CF	PEEK-CF
Continuous operating temperature	up to approximately 100 °C	100 to 180 °C	up to 260 °C
Media contact	Oil, grease, fuel	additionally hot air, coolant	additionally aggressive chemicals, steam
Stiffness requirement	high (10,500 MPa)	high (10,220 MPa)	very high (17,310 MPa)
Sliding and wear load	no	conditional	Yes, tribologically optimized
Budget	cheapest class	middle class	highest class, FGF defused

As a rule of thumb: start with PA-CF and only switch to a higher-grade material if a specific requirement necessitates it. The most common mistake in material selection is not choosing a material that is too weak, but one that is too expensive. This is usually triggered by peak temperatures that only occur for a few minutes a year, or by stiffness requirements that could just as easily have been met by a stiffening rib on the component.

What this means for your request

To provide a reliable recommendation, we need three pieces of information: continuous and peak temperatures and their respective durations, the concentration and temperature of the medium, and the direction of the component load. Based on this information, the material class can usually be determined during a phone call, including whether tempering is required as part of the manufacturing process.

Our material data sheets for PA-CF, PPA-CF and PEEK are available as PDFs upon request and contain all test standards and footnotes. Please contact us at info@malping.de .

Frequently Asked Questions

What are the differences between PA-CF, PPA-CF and PEEK-CF?

All three are carbon fiber-reinforced thermoplastics for FFF printing; they differ in temperature resistance. PA-CF can be used up to approximately 100 °C, PPA-CF (tempered) up to around 180 °C, and PEEK-CF up to a continuous operating temperature of 260 °C. Stiffness and price increase in the same order, but the significant jump in stiffness only occurs between PPA-CF and PEEK-CF.

Up to what temperature can I use PA-CF?

The practical upper limit for PA6-CF15 is around 100 °C, and lower under significant mechanical load. The glass transition temperature is 68 °C; above this temperature, the matrix softens. The datasheet value of 120 °C is a standard heat deflection temperature of 1.8 MPa and does not indicate approval for continuous operation.

Why is PPA-CF more expensive than PA-CF if the stiffness is the same?

At room temperature, it is indeed 10,220 MPa compared to 10,500 MPa. The difference arises above 80 °C. When tempered, PPA-CF25 maintains a heat deflection temperature of 199 °C at 0.45 MPa, while PA6-CF15 is already well above its glass transition temperature in this range. Anyone not exceeding 100 °C doesn't need PPA.

Does PPA need to be tempered after printing?

Yes, if high-temperature properties are required. Untempered, PPA-CF25 achieves a heat deflection temperature of 97 °C at 0.45 MPa; tempered, it reaches 199 °C. Tempering also reduces the Charpy impact strength from 13.1 to 7.3 kJ/m².

How much does the strength of PEEK-CF decrease in the Z-direction?

PEEK-CF30 achieves a tensile strength of 169 MPa and a modulus of elasticity of 17,310 MPa in the XY plane, and 71 MPa and 4,165 MPa, respectively, in the Z direction. This represents approximately 40% of the strength and about a quarter of the stiffness. Therefore, component orientation should be considered during the design phase, not during work preparation.

Which PEEK variant is suitable for medical technology or food contact?

Unreinforced PEEK 450 natural. It is biocompatible, suitable for food contact according to EC 1935/2004, and with an elongation at break of 19%, it is the toughest PEEK variant. PEEK-CF is the choice for stiffness and tribology, while GF-PEEK is used for electrical insulation with increased stiffness.

How large can the components be?

We manufacture PA-CF and PPA-CF using the FFF process up to 350 × 350 × 450 mm. We also produce PEEK using FGF granule printing on the ExAM 510 up to approximately 510 × 510 × 410 mm, which significantly reduces material costs for larger components and small production runs.

What information does Malping need to recommend a material?

Continuous and peak temperatures with their respective time fractions, the medium with its concentration and temperature, and the load direction within the component. With these three pieces of information, the material class can usually be determined in a single phone call.

Author: Dr.-Ing. Bastian Gaedike, Founder and Managing Partner, Malping GmbH, Neuhausen auf den Fildern | malping.de | #MATERIALPENGUIN

Tempering of PEEK, PPS-GF and PPA: What heat treatment really achieves in 3D printing

Diverse Hochleistungskunststoff-Bauteile im Temperofen, Malping GmbH

Short answer: Tempering is a controlled heat treatment after the printing process. For semi-crystalline high-performance polymers, it determines whether the component meets the values specified in the data sheet. The degree of crystallinity of PEEK increases from approximately 17% to over 30%, and according to studies, its tensile strength ranges between 12% and 64%. The hot bending temperature of PPA-CF25 increases from 97°C to 199°C, thus exceeding 100 Kelvin. The heat deflection temperature of PPS-GF20 increases from 125.8°C to 219.6°C under a load of 1.8 MPa. Without heat treatment, these three materials are not high-temperature materials; they are expensive thermoplastics. The disadvantages include longer processing times, higher energy consumption, an increased risk of warpage, and, in the case of PPA, a significant loss of impact strength.

Those who purchase a component made of PEEK , PPS-GF20 , or PPA-CF usually receive a datasheet with excellent specifications – but the final product often fails to meet these requirements. The cause is rarely the printer itself, but rather the crystallinity, which may not develop sufficiently when printing semi-crystalline high-performance plastics.

This article explains when the additional effort for heat treatment is worthwhile, which temperature profiles should be used, and when tempering does more harm than good.

What happens during tempering in the component

Semicrystalline thermoplastics exhibit two characteristic temperatures. At the glass transition point (Tg), the amorphous regions become mobile, while at the melting point (Tm), the crystalline order breaks down. Between these two points lies a region where crystals can form. For PEEK, Victrex specifies a Tg of 143 degrees Celsius (beginning) and 150 degrees Celsius (midpoint), and a Tm of 343 degrees Celsius.

In FFF and FGF processes, each strand cools down within a few seconds. This often happens too quickly for crystallization to occur. The result is a component that has solidified in a partially amorphous state. In a study published in the *International Journal of Advanced Manufacturing Technology* (2024), DSC measurements of untreated FFF-PEEK samples revealed a crystallinity level of 16.6 percent, whereas the filament used already exhibited a crystallinity level of 28.5 percent. The printer had therefore destroyed the order and not restored it.

Tempering solves this problem. It pursues three goals, which Victrex clearly distinguishes in its tempering instructions:

1. Increased crystallinity . Higher crystallinity means higher strength, increased stiffness, reduced water absorption, and better material durability.

2. Reduction of residual stresses . Both the printing process and the subsequent mechanical processing cause stresses in the component that impair its mechanical performance.

3. Ensuring dimensional accuracy during operation . An untempered component exposed to consistently high temperatures recrystallizes during operation. This leads to dimensional changes in the already assembled part. This aspect is often overlooked in inquiries.

A practical tip for evaluating offers: Filament data sheets often fail to specify the temperature at which measurements were taken. This is a crucial detail; in the case of PPA and PPS, it can make all the difference between two completely different materials, as the following illustrations demonstrate. If you find values for injection-molded parts in a data sheet, you should examine them very carefully, as they are generally not applicable to printed components.

PEEK and CF/GF-PEEK: the greatest leverage

PEEK is the material for which tempering is best documented and yields the greatest benefits.

The standard profile used

Victrex describes a four-step process for additively manufactured components:

Step	Specification
Heating	equilibrium temperature to at least 200 degrees Celsius
Hold	1 hour per millimeter of wall thickness
Cool	10 Kelvin per hour, until the system is below 140 degrees Celsius
End	Turn off the oven and let it cool down to room temperature.

The target temperature depends on the intended use. For simple stress relief, Victrex specifies temperatures of up to 230 degrees Celsius, and for maximum crystallinity, 300 degrees Celsius or more. Nowadays, the holding temperature should be at least 20 Kelvin above the maximum operating temperature of the component. Therefore, if a component is designed for continuous use at 180 degrees Celsius, it should not be released at 160 degrees Celsius.

The complete cycle time must be included in the calculation. With a wall thickness of 5 millimeters, a holding time of 5 hours, and a cooling ramp from 220 degrees Celsius to 140 degrees Celsius at a rate of 10 Kelvin per hour, the cycle time is approximately 13 to 15 hours. In the aforementioned study, measurements yielded more than 8 hours and 2.7 kilowatt-hours per sample. Therefore, tempering is an independent manufacturing step with its own cycle time and not a by-product.

What will measurably improve

Investigation	profile	Result
Int. J. Adv. Manuf. Technol. 2024	200 degrees Celsius, 2 hours	Crystallinity increased from 16.6 to 32.1 percent, tensile strength increased from approximately 48 to 61 MPa, and Young's modulus increased from 3.5 to 4.4 GPa.
Polymers 2022 (14, 5521)	220 degrees Celsius, 72 hours, in a quartz sand bed	Tensile strength plus 37 to 64 percent, fracture toughness plus 33 to 45 percent
Polymers 2026 (18, 1694)	100, 150, 200 degrees Celsius, 1 hour each	Post-treatment temperature was the single strongest factor overall, accounting for 56 percent of the tensile strength, ahead of nozzle and bed temperature.
Coatings 2022 (12, 827)	250 degrees Celsius, 6 hours, CF and GF-PEEK	Interlaminar shear strength plus 16 percent, dimensional change and porosity less than 1 percent

For purchasing departments, the results of the "Polymers 2026" study are crucial: Heat treatment has a greater impact on strength than any single printing parameter. A properly tempered component from a basic system can exhibit better properties than an untempered component from an expensive system.

Fiber-reinforced types behave differently.

CF-PEEK and GF-PEEK also benefit from this, but exhibit different property and risk profiles.

A study published in the journal "Coatings" (2022) determined that the optimal conditions for short-fiber-reinforced CF-PEEK and GF-PEEK were a temperature of 250 degrees Celsius for a duration of 6 hours. The improvements achieved through short-fiber reinforcement amounted to over 5 percent in tensile, flexural, and impact strength, and 16 percent in interlaminar shear strength – precisely the area in which printed components are most likely to fail.

Glass fiber reinforced variants prove to be significantly more resistant at high temperatures. A study published in the "Journal of Manufacturing and Materials Processing" (2026) compared unreinforced PEEK with PEEK-GF20. At 250 degrees Celsius, both materials showed improvements. However, at 300 °C, the unreinforced PEEK lost strength due to gas-induced porosity, while no such damage occurred in PEEK-GF20.

The borders that are rarely talked about

• Brittleness. For unreinforced types, Victrex explicitly points out that while high tempering temperatures increase crystallinity, they significantly reduce elongation. A study published in the journal "Polymers" (2023) showed that after treatment at 300 °C for 2 hours, no yield zone was observed, only a purely brittle fracture. Therefore, maximum crystallinity is not a suitable optimization parameter for components that must withstand impact loads or stresses during assembly.

• Surface oxidation. Victrex cites yellowing and surface oxidation as possible consequences of high annealing temperatures. This is particularly important for visible components.

• Warping. Thin-walled or asymmetrical components tend to warp during free annealing. According to Victrex, it is common practice in additive manufacturing (AM) technology to use a sand-like material as a mechanical support. In the aforementioned study, a 72-hour annealing process in quartz sand was used to ensure more uniform heating.

• However, there are also opposing views. Manufacturers of systems that print PEEK in its semi-crystalline state argue that this eliminates the need for subsequent heat treatment and the associated distortion. As an interim solution, hot air treatment during the printing process was investigated: This achieved a degree of crystallinity of 34.9% without additional time expenditure, although the mechanical properties were lower than those of furnace treatment (tensile strength 54 MPa compared to 61 MPa).

  
  

PPS-GF20: the tempering temperature determines the application range

The heat resistance of PPS is significantly lower than that of PEEK. PPS-GF20 has a glass transition temperature of 95 degrees Celsius and a melting point of 279.6 degrees Celsius. However, the crucial figure in the datasheet is the third: the crystallization temperature of 225.8 degrees Celsius. The tempering temperature of 130 degrees Celsius is almost 100 Kelvin lower than the temperature at which PPS actually crystallizes.

This is clearly evident from the values in our own data sheets. These values were determined using test specimens that were tempered for 10 hours at 130 degrees Celsius. If the emission occurs instead at 230 degrees Celsius, the thermal transition temperature changes dramatically.

Key figure	tempered at 130 degrees Celsius, 10 hours	tempered at 230 degrees Celsius	difference
HDT according to ISO 75, 1.8 MPa	125.8 degrees Celsius	219.6 degrees Celsius	plus 93.8 Kelvin
HDT according to ISO 75, 0.45 MPa	236.3 degrees Celsius	248.9 degrees Celsius	plus 12.6 Kelvin

The jump to 1.8 MPa is the most important value for PPS users in this article. Under practical load, the operating temperature nearly doubles. A PPS-GF20 component tempered too low will deform under load at 130 degrees Celsius, while a component tempered at 230 degrees Celsius can withstand temperatures above 200 degrees Celsius. This is not a matter of fine-tuning, but rather a decision about whether PPS-GF20 is even suitable for the application.

It is also revealing that the values hardly differ at low loads (0.45 MPa): Anyone who relies on a nice figure of 0.45 MPa for their design will not notice the difference and will later be surprised by the distortions of the component.

The fact that PPS solidifies practically amorphously without controlled temperature is also well documented in the literature. A study in "Polymers" (2023), focusing on highly glass-fiber-reinforced PPS, found no crystalline peak in the X-ray diffraction pattern at a quenching temperature of 80 °C. Between 80 and 160 °C, the crystallinity index doubled, the tensile strength increased by 10%, the modulus of elasticity by 24%, the flexural strength by 17%, and the absorbed impact energy by 37%.

The most compelling evidence for post-printing heat treatment is the work of Kishore et al. (Additive Manufacturing, 2020) on short lengths of carbon fiber-reinforced PPS from large-format printing. Isothermal annealing at 250 °C for 18 hours improved the storage modulus above Tg for all tested types. This is crucial for PPS: without crystallinity, stiffness drops significantly above approximately 95 degrees Celsius, rendering half of the material's application ranges unusable.

The PPS-specific pitfall: The same study shows thermo-oxidative structural changes on the surface. Very long holding times just above the crystallization temperature (Tg) are no longer considered annealing, but rather aging. A 180-hour aging study of PPS-GF20 at 85–145 degrees Celsius showed a decrease in tensile strength from 130 to 70 MPa and a decrease in elongation at break from 7 to 3 percent, which was attributed to damage to the fiber-matrix interface and chain breakage. Discoloration and loss of gloss correlate measurably with the loss of properties. Therefore, discoloration in PPS is a sign of damage and not merely a cosmetic problem. In practice, this means short, hot annealing in the crystallization temperature range, not long, lukewarm annealing just above Tg.

Regarding the availability of information: For PPS, there is no publicly published emissions profile with heating and cooling rates, unlike the one Victrex provides for PEEK. The defined endpoints are clear; the path to them is taken from the PEEK methodology and verified by the component.

PPA-CF25 and PPA-GF15: without tempering, they are not high-temperature materials.

The effect is greatest with PPA and is illustrated in our own datasheet. Untreated PPA-CF25 is not a high-temperature material. Its temperature regulation temperature is 97 degrees Celsius, which is comparable to that of a well-processed technical polyamide. In the tempered state, it is 199 degrees Celsius.

Key figure	PPA-CF25 untempered	PPA-CF25 tempered	PPA-GF15 untempered	PPA-GF15 tempered
HDT 0.45 MPa (Method B)	97 degrees Celsius	199 degrees Celsius	84 degrees Celsius	185 degrees Celsius
HDT 1.8 MPa (Method A)	84 degrees Celsius	126 degrees Celsius	80 degrees Celsius	112.2 degrees Celsius
Charpy XY, unnotched	13.1 kJ/m²	7.3 kJ/m²	12.2 kJ/m²	7.1 kJ/m²

The heat deflection temperature increases by approximately 100 Kelvin under low stress and by more than 40 Kelvin under high stress. The reason is the same as for PEEK and PPS: PPA has a glass transition temperature of only 80 degrees Celsius and a melting point of 239 degrees Celsius (PPA-CF25) or 232 degrees Celsius (PPA-GF15). Between these points lies a wide window in which the pressure-hardened, amorphous material recrystallizes. Without this step, the order is lost, and consequently, so is the thermal deformation temperature.

The price is listed in the same table. Tempering reduces the Charpy impact strength by over 40 percent, from 13.1 to 7.3 kJ/m² for PPA-CF25 and from 12.2 to 7.1 kJ/m² for PPA-GF15. This is the same mechanism as with embrittlement in PEEK: increased crystallinity, less energy absorption in the crack. For a housing subjected to hot and static loads, replacement is clearly the right choice. If you want a component designed to absorb shocks, you need to make an informed decision.

One more note on interpretation: The XY properties in our PPA datasheet are determined using an annealed sample, while the Z properties are determined using an unannealed sample. Calculating the anisotropy from both columns means working with two different material states.

Drying is not tempering

These two steps are often confused when working with PPA, even though they serve different purposes and take place in different parts:

• Drying involves the filament and takes place before printing. Its purpose is to remove water from the material to prevent hydrolysis, bubbles, and poor layer adhesion in the nozzle .

• Annealing affects the printed component and takes place after printing. Its purpose is to increase crystallinity and reduce internal stresses.

Both are essential for PPA and neither replaces the other. Moisture absorption is significantly higher for PPA than for other materials in this range: 1.09 percent for PPA-CF25 and 1.37 percent for PPA-GF15 according to ISO 62, compared to 0.11 percent at equilibrium for PPS-GF20 and 0.03 percent for unreinforced PEEK.

A study published in the journal "Applied Sciences" (2026) measured the drying time of PPA-CF. Time to 0.6 percent residual moisture:

Drying temperature	Time until 0.6 percent residual moisture
70 degrees Celsius	approximately 67 hours
95 degrees Celsius	approximately 6 hours
120 degrees Celsius	approximately 1.3 hours

The 50-fold difference between 70 and 120 degrees Celsius is the strongest argument against the common practice of producing PPA in a standard filament dryer at 70 degrees Celsius. 3DXTech's manufacturer recommendation for PPA and HTN is 120 degrees Celsius for 4 hours.

Be careful with the nomenclature: The designations PPA, HTN, PA6T, and PA10T refer to copolyamides that differ significantly in some respects. Our PPA-CF25 melts at 239 degrees Celsius, while other types marketed as PPA melt between 285 and 315 degrees Celsius, according to technical literature. Mixing the properties of different products leads to misinterpretations, including regarding the temperature profile. Always request the product data sheet for the specific type you are using.

Three questions for every datasheet

The figures above illustrate why the characteristic value is of little significance without considering the temperature state. PPA-CF25 has a heat deflection temperature of 97 or 199 degrees Celsius depending on the temperature state, while PPS-GF20 exhibits a temperature of 125.8 or 219.6 degrees Celsius at a load of 1.8 MPa. It is the same material, the same component, the same geometry.

Therefore, check the following information in every offer and every data sheet:

• In what release state was the measurement performed? Uncoated, lightly coated, or at crystallization temperature? If this information is missing, the value is not suitable for design purposes.

• At what load does the heat deflection temperature apply? 0.45 MPa or 1.8 MPa? For PPS-GF20, these two values differ by more than 110 Kelvin and are affected very differently by the release.

• Does this value apply to a printed or injection-molded component? Injection-molded values cannot be transferred, even partially, to printed components.

Therefore, our material data sheets specify the temperature status for each changed characteristic value, including values that deteriorate due to emission.

Material comparison at a glance

	PEEK / CF-PEEK / GF-PEEK	PPS-GF20	PPA-CF25 / PPA-GF15
Glass transition Tg	143 degrees Celsius	95 degrees Celsius	80 degrees Celsius
Melting point Tm	343 degrees Celsius	279.6 degrees Celsius	239 or 232 degrees Celsius
Crystallization temperature	200 to 300 degrees Celsius in the window	225.8 degrees Celsius	between Tg and Tm
Sensible temperature level	200 to 250 degrees Celsius, for maximum crystallinity up to 300 degrees Celsius	Approximately 230 degrees Celsius, significantly more effective than 130 degrees Celsius	According to the manufacturer's instructions for the compound, the effect is shown in the data sheet.
Proven benefits	Crystallinity increased from 17 to over 30 percent, tensile strength increased by 12 to 64 percent.	HDT at 1.8 MPa increased from 125.8 to 219.6 degrees Celsius	HDT at 0.45 MPa from 97 to 199 degrees Celsius (CF25)
Price of tempering	Loss of ductility, oxidation risk	Oxidative damage due to incorrect profiling; discoloration as a warning signal	Impact resistance reduced by over 40 percent
Additionally, please note	Delay, processing time 8 to 15 hours	short and hot instead of long and lukewarm	Dry the filament at 120 degrees Celsius before printing.
Maximum component size at Malping	510 x 510 x 410 mm (FGF)	up to 300 mm (FFF)	350 x 350 x 450 mm (FFF)

When to temper and when not to temper

With PPS-GF20 and PPA, the question is usually already answered: Without tempering, these materials do not offer the heat resistance for which they were selected. Using PPA-CF25 without tempering means buying a material rated for 199 degrees Celsius, but only achieving 97 degrees Celsius. With PEEK, the situation is more open, as even a PEEK component made without tempering is often still a very good component.

Tempering is worthwhile if at least one of the following points applies:

• The material is PPS-GF20 or PPA, and the component is designed for operation at high temperatures. This is the clearest example, as can be seen in the images above.

• The component operates continuously at temperatures above 100 degrees Celsius, or in the case of PEEK, at temperatures above 140 degrees Celsius. Otherwise, it recrystallizes during operation and changes its dimensions.

• It comes into contact with media, cleaning chemicals, or hot steam. Higher crystallinity reduces absorption and corrosion.

• It is subject to continuous stress and does not creep. Creep strengths in data sheets are usually determined using hardened samples, typically PEEK that has been cured for 2 hours at 200 degrees Celsius.

• It is processed and must retain its dimensions afterwards.

• Stiffness and strength are crucial for the design, and the data sheet was provided in printed form.

Do not temper if:

• the component is a room temperature device, a prototype, or an assembly device.

• Toughness and impact resistance are more important than stiffness and heat resistance. When tempering PPA, the impact strength decreases by more than 40 percent; this is a real compromise, not just a formality.

• the geometry is thin-walled, large-area and asymmetrical, and the risk of deformation outweighs the benefit,

• The delivery time is crucial and none of the above points apply.

It is important that this decision is made consciously and taken into account in the offer. The untempered PPA component is not wrong; it is simply a different component.

The order in the process is crucial.

A crucial detail that determines the dimensional accuracy of the finished part: first tempering, then machining.

Annealing alters the dimensions. Even under optimal conditions, the dimensional change can be up to 1 percent, as studies with CF and GF-PEEK coatings at 250 degrees Celsius for 6 hours have shown. Machining a fitting or thread before annealing is essentially machining it twice.

The machining process itself creates stresses within the component. For highly stressed parts, a second, milder annealing cycle after machining can therefore be particularly beneficial to relieve stresses and prevent crystallinity. Victrex specifically mentions this scenario as an application of tempering.

The malping process proceeds as follows:

• Drying of the filament or granules, followed by printing using the FFF or FGF process.

• Tempering according to material- and wall thickness-specific profile, with mechanical support for critical geometries.

• Machining of functional surfaces and threads by our qualified CNC partner (threads from M8).

• Dimensional control, possibly with optical digitization using our 3D scanner.

• Optional second stress reduction cycle.

General tolerances: FFF ±0.2 mm, FGF ±0.2–0.5 mm, CNC-machined ±0.05 mm. FFF production volume: max. 350 x 350 x 450 mm. FGF production volume: 510 x 510 x 410 mm.

What this means for your request

You don't need to specify a temperature profile. It would be helpful if you could tell us three things:

• Continuous fluctuations in operating temperature and component temperature

• Media contact, cleaning methods and sterilization

• Critical dimensions with tolerances so that we can determine what is produced before and after tempering.

We process PEEK, CF-PEEK, and GF-PEEK in technical and medical grades, as well as PPS-GF20, PPA-CF25, and PPA-GF15. The standard lead time is two weeks and includes tempering. Our material data sheets specify the tempering status for each material, even if tempering would reduce its value.

Request a component or go directly to PEEK manufacturing according to drawing .

Frequently asked questions about tempering high-performance polymers

What is tempering in 3D printing?

Tempering is a controlled heat treatment performed after printing. The component is heated in a furnace to a temperature between the glass transition point and the melting point, held at this temperature, and then slowly cooled. The aim is to increase crystallinity and eliminate internal stresses.

At what temperature is PEEK tempered?

Victrex specifies temperatures up to 230 degrees Celsius for stress relief and 300 degrees Celsius and higher for high crystallinity. In practice, temperatures of 200–250 degrees Celsius are common. The holding time is approximately one hour per millimeter of wall thickness, and cooling occurs at a rate of about 10 Kelvin per hour to below 140 degrees Celsius.

How much strength does tempered PEEK gain?

The published values range from plus 12 to plus 64 percent tensile strength, depending on profile, fill level, and web orientation. The degree of crystallinity typically increases from around 17 to over 30 percent.

Can tempering damage a component?

Yes, and measurably so. The Charpy impact strength of PPA decreases by more than 40 percent due to emissions, from 13.1 kJ/m² to 7.3 kJ/m² in the case of PPA-CF25. Excessively high temperatures embrittle unreinforced PEEK, leading to pure brittle fracture and potentially surface oxidation; gas-induced porosity has been observed in unreinforced PEEK at 300 degrees Celsius. For PPS, prolonged holding times just above the glass transition temperature tend to lead to aging rather than improvement. Emission is therefore always a compromise: heat resistance and stiffness versus toughness.

Does a component warp during tempering?

The risk is particularly high with thin-walled, large-area, or asymmetrical parts. In additive manufacturing, it is common practice to mechanically support components in a sandy medium during annealing. The dimensional change itself is less than one percent under good conditions, but it must be taken into account in the manufacturing process.

Do PPS-GF20 components need to be tempered?

Yes, if the component is intended for operation at high temperatures and under load. A crucial factor is the annealing temperature: After 10 hours at 130 degrees Celsius, the thermal resistance under a load of 1.8 MPa is 125.8 degrees Celsius, while annealing at 230 degrees Celsius results in a temperature of 219.6 degrees Celsius. That's a difference of almost 94 Kelvin for an identical component. The reason: The crystallization temperature of PPS-GF20 is 225.8 degrees Celsius, so annealing at 130 degrees Celsius is significantly below the material's actual crystallization temperature.

Does PPA need to be tempered?

Yes. Uncured PPA is not a high-temperature material. The heat deflection temperature at 0.45 MPa increases with tempering from 97 °C to 199 °C for PPA-CF25 and from 84 °C to 185 °C for PPA-GF15, which corresponds to approximately 100 Kelvin. At 1.8 MPa, the increase is from 84 °C to 126 °C and from 80 °C to 112.2 °C, respectively. Using uncured PPA means paying for a high-temperature material but achieving the heat deflection temperature of an engineering polyamide. However, tempering also results in a loss of impact strength of over 40%.

Is drying the same as tempering?

No, these are two separate steps with different purposes. The filament is dried before printing to prevent hydrolysis and bubbles in the nozzle. The finished part is annealed after printing to increase crystallinity and eliminate internal stresses.

How can I tell if a datasheet value is considered tempered?

It is essential to ensure that the value is clearly specified. If this information is missing, the value is uninterpretable, as the heat deflection temperatures of PPA and PPS can differ by up to 100 Kelvin between the annealed and unannealed states. Furthermore, it is crucial to note the stress at which the heat deflection temperature is applied (0.45 or 1.8 MPa) and whether the value is determined using a printed or injection-molded sample.

Tempering before or after machining?

Generally, tempering should be performed first, followed by machining of fits, functional surfaces, and threads, as tempering alters the dimensions. For highly stressed components, a second, milder cycle after machining may be beneficial to relieve the accumulated stresses.

Sources

• Malping material data sheets PEEK, PPS-GF20 and PPA-CF25/PPA-GF15 (printed test specimens, as of 2026)

• Victrex, Additive Manufacturing Annealing Guidelines, V.3, November 2021:victrex.com

• Victrex, PEEK finishing operations guide, January 2022:victrex.com

• Victrex PEEK 450G datasheet:victrex.com

• Int. J. Adv. Manuf. Technol. 2024: link.springer.com

• Polymers 2022, 14, 5521:mdpi.com

• Polymers 2026, 18, 1694:mdpi.com

• Polymers 2023, 15, 2209:mdpi.com

• Coatings 2022, 12, 827:mdpi.com

• JMMP 2026, 10, 110:mdpi.com

• Kishore et al., Additive Manufacturing 2020: doi.org

• Polymers 2023, 15, 3179:mdpi.com

• Polymers 2022, 14, 1275:mdpi.com

• Applied Sciences 2026, 16, 5056:mdpi.com

• Ensinger, PPS material information: ensingerplastics.com

• 3DXTech, Filament Drying Instructions:3dxtech.com

PEEK-GF20 vs. PPS-GF20 for electrical applications

High-voltage components & circuit board holders in FFF 3D printing

At a glance

→ PEEK-GF20 and PPS-GF20 are the preferred materials for high-performance electrical applications in FFF 3D printing.

→ Crucial factors: temperature requirement, tracking resistance (CTI), flame retardancy class and cost sensitivity

→ FFF/FDM is the right process for these component classes — geometric complexity with manageable batch size

→ Malping processes both materials on industrial FFF systems with PCD nozzles.

Why use glass fiber reinforced high-performance polymers in electrical engineering?

Electrical and electronic components place demands on their materials that quickly push conventional engineering plastics such as PA6, ABS, or PC to their limits: high continuous operating temperatures, defined tracking resistance, flame retardancy according to UL 94, and mechanical stability even under the influence of moisture. This is precisely where glass fiber-reinforced high-performance polymers come into play.

PEEK-GF20 (polyetheretherketone with 20% glass fiber) and PPS-GF20 (polyphenylene sulfide with 20% glass fiber) are established materials in electrical engineering and both can now be reliably processed using FFF 3D printing.

This opens up completely new possibilities: customer-specific insulators, circuit board holders and connector housings that would be expensive or time-consuming to produce using traditional manufacturing methods.

This article systematically compares PEEK-GF20 and PPS-GF20 with a view to typical electrical applications such as high-voltage components and circuit board holders, and provides clear decision-making support for material selection.

PEEK-GF20 vs. PPS-GF20: The most important properties compared

The following table compares the material properties relevant for electrical applications. All values refer to printed components (FFF); mass-produced injection-molded components may differ.

Characteristic	PEEK-GF20	PPS-GF20
fiber optic component	20 wt.%	20 wt.%
Continuous operating temperature	up to 260 °C	up to 220 °C
Tracking resistance (CTI)	≥ 100 (PTI)	≥ 600 (PLC 0)
Flame retardant class (UL 94)	V-0 (1.5 mm)	V-0 (0.8 mm)
Tensile strength	approx. 120–140 MPa	approx. 90–110 MPa
E-module	approx. 8–10 GPa	approx. 7–9 GPa
density	approx. 1.35 g/cm³	approx. 1.45 g/cm³
Water absorption (23 °C/50%RH)	< 0.3%	< 0.02%
Chemical resistance	Very high	High
Media resistance (oils/fats)	Very high	High
Processing temperature (FFF)	approx. 390–420 °C	approx. 310–360 °C
Print bed temperature (FFF)	approx. 120–160 °C	approx. 100–130 °C
Filament material costs	500–700 €/kg	150–250 €/kg
Price/performance ratio	★★★☆☆	★★★★★
Typical application area	High voltage, high temperature	PCB holders, standard HV

¹ CTI according to IEC 60112; ² Tensile strength ISO 527 (printed specimens, printing direction XY); ³ Filament prices Malping purchasing as of 2025

High-voltage applications: Leakage resistance as a key property

What does tracking resistance (CTI) mean?

The Comparative Tracking Index (CTI) describes a plastic's resistance to the formation of conductive tracking paths on its surface, a safety-critical parameter in high-voltage technology. The higher the CTI value, the better.

PPS-GF20 achieves a CTI ≥ 600 (PLC 0) and is therefore in the highest tracking resistance class — ideal for HV applications up to approximately 1 kV nominal voltage. PEEK-GF20 typically has a CTI ≥ 100 (PTI class) — sufficient for many applications, but requires careful testing for very high voltage classes.

Typical high-voltage components in FFF 3D printing

• Insulators and insulating pieces in switch cabinets and control systems

• Coil carriers and winding bodies for transformers and relays

• Busbar mounts and cable guides for > 400 V

• Connector housings and contact carriers in charging technology (EV sector)

• Sensor mounts in HV environments (vehicle, industry)

For high-voltage applications below 1 kV, PPS-GF20 is in most cases the more economically viable choice : equally good or better CTI value, very good flame retardancy (UL 94 V-0 from 0.8 mm wall thickness) — at significantly lower material costs. PEEK-GF20 is justified when additional requirements include extreme temperatures (> 220 °C continuous load), mechanical wear resistance, or special chemical resistance.

PCB holders: dimensional stability, fit and reproducibility

Requirements profile for circuit board holders

PCB holders must be manufactured reproducibly, as the hole pattern and mounting geometry must precisely match the circuit board. Typical requirements:

• Dimensional stability: low tendency to warp, defined tolerances

• Electrical insulation: no conductivity, sufficient tracking resistance

• Temperature resistance: often increased operating temperature due to power dissipation from adjacent components

• Ease of assembly: Snap connections, screw bosses, insert parts

• Flame retardancy: UL 94 V-0 often required, especially for power supplies and power electronics

PPS-GF20 perfectly meets the requirements for circuit board holders : excellent tracking resistance (PLC 0), UL 94 V-0 even with thin wall thicknesses, very low moisture absorption (< 0.02%) for dimensionally stable fits—all at a fraction of the cost of PEEK-GF20. For standard applications up to approximately 150–180 °C, PPS-GF20 is the economically superior choice.

When is PEEK-GF20 used for circuit board holders?

PEEK-GF20 is chosen for circuit board holders when:

• The operating temperature is permanently > 200 °C (e.g. near power modules or in high-temperature furnaces)

• Aggressive cleaning agents or solvents are used against which PPS shows weaknesses

• Sterilizability (e.g., steam sterilization) is required

• Particularly high mechanical load peaks occur — PEEK-GF20 has the higher tensile strength

Why FFF/FDM is the right process for these component classes

High-voltage components and circuit board holders share a characteristic feature in practice: they are often geometrically complex and, at the same time, rarely required in large production volumes. This is precisely what plays into FFF's hands.

FFF enables: component complexity without tooling costs, fast design iterations (First Article in days instead of weeks), economical batch sizes of 1–1000 pieces, and the direct processing of certified high-performance polymers.

Compared to FGF granule printing (which excels in very large components and high production volumes), FFF offers clear advantages for this component class: higher detail resolution, finer wall thicknesses, better reproducibility for small features, and PEEK-GF20 and PPS-GF20 are available as industrial-grade filaments.

FFF processing instructions for PEEK-GF20 and PPS-GF20

→ PEEK-GF20: Printing temperature 390–420 °C, bed 120–160 °C, closed heating chamber required

→ PPS-GF20: Printing temperature 310–360 °C, bed 100–130 °C, closed heating chamber recommended

→ Both materials: PCD (polycrystalline diamond) nozzles are mandatory for abrasive fiberglass compounds

→ Drying before printing: PEEK-GF20 min. 4–6 h at 150 °C, PPS-GF20 min. 4 h at 120 °C

→ Optimal layer thickness: 0.10–0.20 mm for electrically relevant detail geometries

Decision matrix: PEEK-GF20 or PPS-GF20?

Application scenario	PEEK-GF20	PPS-GF20
High voltage > 1 kV (continuous operation)	✅ First choice	⚠️ Check
High voltage < 1 kV	✅ Possible	✅ First choice
Circuit board holder (standard)	⚠️ Oversized	✅ First choice
PCB holder (high temperature)	✅ First choice	⚠️ Border area
Humid environment / Condensation	✅ Very good	✅ Very good
Aggressive chemicals	✅ Very good	✅ Good
Weight-critical components	✅ Lighter	⚠️ Heavier
Cost-sensitive project	⚠️ More expensive	✅ Cheaper
Sterilizability (steam)	✅ Possible	✅ Possible
UL 94 V-0 for thin wall thicknesses	⚠️ From 1.5 mm	✅ From 0.8 mm

✅ = recommended / first choice | ⚠️ = possible, but consultation recommended | Information applies to FFF-printed components

Practical examples from everyday Malping life

Example 1: High-voltage insulating piece for industrial frequency converter

A machine manufacturer needed a custom-made insulating piece for the high-voltage input section of a frequency converter (600 V DC). Requirements included UL 94 V-0, CTI Class PLC 0, and an operating temperature of up to 130 °C. The geometry, with integrated cable channels and asymmetrical connectors, was complex for conventional CNC manufacturing.

Material: PPS-GF20 via FFF — Delivery time 4 working days from approval, including quality inspection. The component met all electrical and mechanical requirements in the first-article test.

Example 2: Circuit board holders for power electronics test setup

An electronics company needed 12 different circuit board adapter holders for a test bench operating at high ambient temperatures (> 160 °C). Standard holders made of PA or PC failed due to warping.

Material: PPS-GF20 for 9 of 12 variants, PEEK-GF20 for 3 variants with temperatures > 200 °C – a cost-optimized mixing strategy that was only economically feasible through 3D printing without tooling requirements.

Example 3: Sensor mount in the vehicle's high-voltage system

A temperature and pressure sensor mount was developed for an automotive supplier in the high-voltage battery area. Requirements: continuous operating temperature of 220 °C, resistance to electrolyte vapors, UL 94 V-0.

Material: PEEK-GF20; the superior chemical resistance and high-temperature stability justified the higher price compared to PPS-GF20.

FAQ — Frequently Asked Questions

Are PEEK-GF20 and PPS-GF20 certified for high-voltage applications using FFF 3D printing?

The materials themselves are UL-94 listed. For printed components in safety-critical high-voltage systems, component-specific qualification (e.g., according to IEC 61439 or customer requirements) is required by the user. Malping provides complete material certificates and test reports upon request.

What are the minimum wall thicknesses achievable with PEEK-GF20 and PPS-GF20 in FFF printing?

In practice, wall thicknesses from approximately 0.5 mm (1 perimeter) can be reliably produced. For electrically relevant insulation gaps, we recommend a wall thickness of at least 1.5–2.0 mm to eliminate process-related pores.

Can Malping also produce larger series of circuit board holders?

Yes, FFF is economical for up to approximately 1000 units per variant. For larger production runs, we recommend a cost comparison with injection molding or granulate 3D printing (FGF). Malping provides transparent advice to help you decide whether to make or buy.

How do PEEK-GF20 and unfilled PEEK differ for electrical applications?

Unfilled PEEK has lower stiffness and higher toughness. Due to its glass fiber content, PEEK-GF20 offers a higher modulus of elasticity and better dimensional stability under heat. For dimensionally stable brackets and structural components, the GF20 variant is almost always preferable. The CTI value is comparable for both.

How long does it take to deliver prototypes?

Standard delivery time for FFF prototypes made of PEEK-GF20 or PPS-GF20: 10 working days from order confirmation and approved CAD data. Express deliveries (3-4 working days) are also possible.

Conclusion: The right material for your electrical application

PEEK-GF20 and PPS-GF20 are complementary materials, not competitors. The choice depends on temperature requirements, tracking class, flame retardancy, and cost sensitivity. As a rule of thumb:

• PPS-GF20: Standard high voltage and PCB mounting up to 200 °C. Excellent CTI, best cost-performance ratio.

• PEEK-GF20: When additional extreme temperatures, chemical resistance or maximum mechanical strength are required.

Your next step

→ Send STEP file and/or PDF drawing to: info@malping.de

→ We check geometry and material suitability free of charge — and recommend the optimal material

→ We will respond to your offer or inquiries within 24 hours (working days)

→ malping.de

About the author: Dr.-Ing. Bastian Gaedike is the founder and managing director of Malping GmbH (brand: Materialpinguin) in Neuhausen auf den Fildern. The materials scientist, who holds a doctorate, specializes in the processing of high-performance polymers using FFF and FGF (granulate printing) as well as their CNC post-processing.