Choosing between engineering plastic bearings and PTFE composite bearings is not simply a choice between plastic and PTFE. It is a choice between two different bearing constructions with different structural, environmental, and operating characteristics. The wrong choice can lead to insufficient load capacity, dimensional changes with temperature or moisture, accelerated wear, or unsuitable running clearance—problems that may only appear after the equipment enters production.

Both bearing types belong to the broader family of self-lubricating or low-lubrication bearings. However, they use different material systems, structural designs, and sliding mechanisms. Each has advantages depending on the application. This guide compares the two construction routes—reinforced engineering plastic (MG-EPB) and metal-backed PTFE composite (MG-1)—and explains when OEM buyers should evaluate each.

Terminology note: In this article, “engineering plastic bearing” refers specifically to the MG-EPB reinforced polymer-based construction, while “PTFE composite bearing” refers specifically to the MG-1 metal-backed PTFE composite construction. These are representative product constructions used for comparison rather than definitions of all engineering plastic or PTFE composite bearings. 

1. What Are Engineering Plastic and PTFE Composite Bearings?

Engineering Plastic Bearings (MG-EPB)

MG-EPB bearings use an engineering plastic as the base material, combined with reinforcing agents and lubricants, and produced through thermal molding. The resulting polymer-based structure is used for dry-running bearing applications where weight, environmental resistance, electrical insulation characteristics, and production requirements need to be considered. For a detailed product overview, see MG-EPB Engineering Plastic Bearings.

PTFE Composite Bearings (MG-1)

MG-1 uses a layered construction consisting of a PTFE compound sliding layer, porous bronze interlayer, steel backing, and plating. During dry sliding, the PTFE-based layer can form a transfer film on the mating surface, supporting the bearing’s low-friction sliding behavior. MG-1 is suitable for rotary and oscillating movement and can operate in dry-running or lubricated conditions. For a detailed selection framework, see our PTFE Composite Bearing Selection Guide.

Core difference: MG-EPB is a polymer-based construction in which material modification improves rigidity, dimensional stability, wear resistance, and environmental resistance, while its non-metallic construction can also support lightweight designs. MG-1 is a metal-backed composite construction—its operating characteristics come from the combination of the metal-backed structure and PTFE sliding layer.

2. Engineering Plastic vs PTFE Composite: Performance Differences

The table below summarizes the main differences between the two construction routes. Final selection depends on the complete operating conditions and validated product data.

Note: Product-specific values are shown only where published for the corresponding series. An application-dependent item requires verification against the selected material grade, geometry, and operating conditions rather than comparison by material category alone.

*According to MG-1 product data; actual friction depends on operating conditions and mating components.

Key observations:

• Transfer film — a key mechanism in MG-1: During dry sliding, the PTFE-based sliding layer can form a transfer film on the mating metal surface. This film contributes to low-friction behavior and helps protect the mating surface. This mechanism is one reason PTFE composite bearings can be used in dry-running applications.

• Dry + lubricated operation (MG-1 flexibility): MG-1 is not limited to dry running and can also be used under lubricated conditions where required by the application.

• Electrical insulation (MG-EPB difference): MG-EPB’s non-metallic construction can provide electrical insulation characteristics. MG-1’s metal-backed construction does not provide insulation; electrical isolation requirements need separate evaluation.

• Moisture and swelling: Both constructions address moisture absorption, but through different material systems. MG-EPB uses low-moisture-absorption polymer materials; MG-1 uses a composite material system designed to provide lower water absorption and reduced swelling.

MG-1’s load, PV, temperature, and friction data are product-specific and should not be generalized to all PTFE composite bearings. MG-EPB performance depends on its specific material formulation, geometry, and operating conditions. For a detailed comparison of PTFE composite and bronze bearings, see our PTFE Composite Bearings vs Bronze Bearings selection guide.

3. How to Choose Between Engineering Plastic and PTFE Composite Bearings

A practical selection process should start with the complete operating system—not simply the bearing material. The following factors help determine which construction route to evaluate first.

1. Motion

MG-1 is specified for rotary and oscillating movement. For other motion types, suitability should be checked against the specific material formulation and application conditions.

2. Load and PV

MG-1 has product-specific load and PV data for engineering verification, including a 250 N/mm² static load rating, 1.8 N/mm²·m/s continuous PV, and 3.6 N/mm²·m/s short-term PV. These values are specific to MG-1 and should not be generalized to PTFE composite bearings as a category. MG-EPB load capability depends on its specific formulation, geometry, and operating conditions; the relevant product specification should be checked.

3. Lubrication

MG-EPB is designed for dry operation without external lubrication. MG-1 is specified for dry-running applications and can also be used under lubricated conditions. The lubrication condition should be defined before final material selection.

4. Temperature

For MG-1, verify the application temperature against the stated −195°C to +280°C product range. For MG-EPB, the applicable temperature limit depends on the material formulation and should be confirmed from the product specification.

5. Moisture and Chemicals

For washdown or chemical environments, compare the cleaning medium, temperature, exposure frequency, moisture absorption, and dimensional requirements before selecting the construction. MG-EPB may be considered where non-metallic construction, low moisture absorption, and electrical insulation characteristics are relevant. MG-1 may be considered where a metal-backed construction is required, with backing material matched to the environment.

6. Electrical Insulation

MG-EPB’s non-metallic construction can provide electrical insulation characteristics. MG-1 uses a metal backing, so electrical isolation requirements need separate evaluation.

7. Weight and Space

MG-EPB uses a non-metallic, lightweight construction. MG-1 uses a metal-backed construction. The choice depends on whether weight reduction or structural support is the priority.

8. Production Volume and Supplier Capability

MG-EPB’s molded construction may be relevant for high-volume production. For MG-1, control of the multiple material layers and manufacturing processes should be verified. Production volume, dimensional consistency, traceability, and supplier capability should be confirmed before final selection.

4. Quick Selection Guide: Which Construction Should You Start Evaluating?

The table below is a starting point, not a one-to-one rule. Final selection depends on the complete operating conditions and validated product data.

5. Application Examples

The table below maps common application contexts to bearing construction routes that may be considered. These are starting points rather than one-to-one rules.

For a broader framework covering material selection, cost, and supplier evaluation, see our Composite Bearing Selection Guide for OEM Buyers.

6. What OEM Buyers Should Confirm Before RFQ Approval

Before approving a bearing selection for RFQ, OEM buyers should confirm the following:

Before RFQ

• Drawing and dimensions

• Operating conditions (load, speed, motion, temperature)

• Shaft specification (material, hardness, surface finish)

• Material requirements and lubrication condition

• Current bearing specification, replacement reason, or observed failure issue, if applicable

During Sample Approval

• Dimensional inspection record

• Material certificate

• Agreed test requirements and validation results

Before Mass Production

• Batch consistency and inspection records

• Traceability method

• Change control procedure

For a deeper look at how manufacturing, customization, and quality control are managed, see our OEM Composite Bearings: Customization, Materials, Manufacturing & Quality Control guide. For buyers sourcing from China, supplier verification is an additional critical step—see our Importing Composite Bearings from China: What Industrial Buyers Should Verify guide.

7. FAQ: Engineering Plastic vs PTFE Composite Bearings

Do engineering plastic bearings need a metal backing?
No. MG-EPB uses a polymer-based construction without a metal backing. Its load capability and dimensional stability depend on the reinforced material formulation, bearing geometry, and operating conditions. Metal-backed constructions such as MG-1 use a steel backing to provide structural support and are used where a metal-backed structure is required by the application design.

Can both engineering plastic and PTFE composite bearings run dry?
Both MG-EPB and MG-1 are designed for dry-running applications, but their operating mechanisms and applicable limits differ. MG-EPB relies on its engineered polymer material system, while MG-1 uses a PTFE-based sliding layer and transfer-film mechanism. Actual suitability should be checked against load, speed, PV, temperature, and shaft conditions.

What is the difference between MG-EPB and MG-1?
MG-EPB is a polymer-based construction with reinforcing agents and lubricants. MG-1 is a metal-backed composite with a PTFE sliding layer. Each construction has different structural, thermal, and electrical characteristics.

Which bearing construction is suitable for washdown applications?
The choice depends on the cleaning medium, temperature, exposure frequency, moisture absorption, and structural requirements. MG-EPB may be considered where non-metallic construction, low moisture absorption, and electrical insulation characteristics are relevant. MG-1 may be considered where a metal-backed construction is required, with backing material matched to the environment.

What information should I provide when requesting a bearing quotation?
Drawing, load, speed, motion, lubrication, shaft specification, operating temperature, and annual demand.

8. Send Your Bearing Requirements

If you are comparing MG-EPB and MG-1 for an OEM application, send us the available application data for a technical review.

Please include:

• Bearing drawing or dimensions

• Load and speed

• Rotary, oscillating, or other motion

• Operating temperature

• Dry or lubricated operation

• Shaft material, hardness, and surface finish

• Water, chemical, or contamination exposure

• Current bearing specification or failure issue, if applicable

• Estimated annual demand or order quantity

Our team can review the application requirements and discuss the appropriate bearing construction, material, and validation requirements before quotation or sampling.