Polyimide and hybrid bonds
Polyimide and hybrid bonds are among the highest-performing bond systems for diamond and CBN grinding wheels. The following overview summarises why polyimide has the advantage over conventional resin bonds, when a hybrid bond is the better choice, and in which fields both systems have proven themselves.
Why polyimide bonds?
Compared with other polymers as well as with phenolic and epoxy resins, polyimides offer the highest thermal stability. Depending on the process, standard resin bonds based on phenolic resin withstand up to approximately 180 °C; polyimide-bonded wheels remain dimensionally stable into the range of 300 to 350 °C. This stability combined with extremely high strength makes polyimide the first choice for high-quality diamond and CBN grinding wheels.
For leading tool manufacturers, high production volumes, best quality and low unit costs are the decisive criteria. Polyimide bonds provide the basis for this: cool grinding, high cutting ability and an elastic grain retention that avoids edge chipping and grinding burn.
Key figures at a glance
- 300–350 °C – thermal capability of a polyimide bond
- approx. 180 °C – reference value for a phenolic resin bond
- > 100 m/s – metal bond within the hybrid composite
Why hybrid bonds?
Hybrid bonds combine a polyimide and a metal bond in a single bond system. They meet the high demands of modern series production and unite the advantages of both systems: the grinding characteristics and elasticity of the polyimide bond with the wear and heat resistance of the metal bond.
The result in practice: shorter cycle times with consistent profile accuracy – while requiring less dressing.
Properties compared
| Bond | Temperature | Elasticity | Wear resistance | Typical application |
|---|---|---|---|---|
| Phenolic resin | up to approx. 180 °C | high | low | resharpening, non-critical processes |
| Polyimide | 300–350 °C | high | medium to high | carbide and HSS rotary tools |
| Hybrid (polyimide + metal) | 300–350 °C | medium to high | very high | series production with high infeed |
| Sintered metal | very high | low | very high | high-speed grinding > 100 m/s |
This classification is intended as guidance. Binding values result from the specification, the cooling and the process parameters.
Your advantages with hybrid bonds
- Best grinding characteristics and elasticity of the polyimide bond
- High wear and heat resistance of the metal bond
- Improved cycle time in production
- High infeed possible
- Reduced dressing volume
- Lower residual stress, no grinding burn
- Improved surface and edge quality
- Reduced loading of the wheel
- Longer tool life and profile retention
- Energy-efficient process
Fields of application
Rotary tools
Drills, milling cutters and step tools made of carbide – flute, back and peripheral grinding.
HSS tools
CBN specifications for high-speed steel, saws and profile tools.
CNC series production
Long-running processes with high infeed, where dressing intervals and cycle time matter.
Data sheet and consulting
All details at a glance as a PDF: Polyimide and hybrid bonds (PDF, English) View
We match grit size, concentration and bond hardness to your process. The values stated are typical guide values and depend on the process.
Contact: genc@ehwadia.de