Specifications
| Parameter | Specification |
|---|---|
| Material | Stainless AISI 304 / 316 / 17-4PH; aluminium A356-T6 on request |
| Process | Silica sol lost wax investment casting + CNC turning, threading and milling |
| Tolerance | ISO 8062 CT5-CT6 as-cast; machined seal bore and thread to +/- 0.02 mm, ISO 2768-f |
| Surface finish | As-cast Ra 6.3 um, machined Ra 1.6 um, ASTM A967 passivation or anodising optional |
| Weight range | 0.09 – 0.62 kg per part |
| Heat treatment | Solution anneal, or H900/H1075 ageing for 17-4PH grades |
| Inspection | CMM and thread gauge inspection, concentricity check, surface roughness, dye penetrant, tensile per ASTM E8 |
Key features
- Cast thread relief and seal pocket reduce material removal and keep the grain structure intact at the sealing diameter.
- CNC turned seal bore held to H7 with 1.6 um Ra for long life of the rack shaft oil seal.
- Thread pitch diameter verified with go and no-go gauges, with concentricity to the seal bore inside 0.03 mm.
- 316 stainless or A356-T6 aluminium options cover both corrosion-critical and weight-sensitive steering designs.
- Passivation per ASTM A967 ensures consistent corrosion resistance against road salt and humidity ingress.
- Cast-in hex or spanner flats allow controlled torque assembly on the customer line without extra machining.
- Dimensional capability maintained on all sealing and thread characteristics identified as critical.
Applications
- Electric power steering rack housing end closures
- Rack and pinion steering gear end caps
- Steer-by-wire actuator housing closures
- Column assist and pinion assist EPS units
- Commercial vehicle hydraulic steering rack end caps
- Steering system remanufacturing and service parts
Quality & compliance
End caps are produced under our IATF 16949 certified quality system with sealing and thread features classified as critical characteristics. PPAP level 3 documentation is available, covering DFMEA and PFMEA, control plan, MSA, dimensional reports, material certification, heat treat charts, passivation records and PSW. IMDS entries are submitted on request, and every part is traceable to its heat lot and machining batch.
FAQ
Q1. Can you cast the thread instead of machining it?
For coarse threads we can cast the thread form and finish chase it on the CNC lathe, reducing cycle time. Fine or sealing threads are fully machined to guarantee gauge compliance.
Q2. How do you guarantee the end cap seals?
The seal bore is finish turned to size and surface finish specification, then checked for roundness and concentricity to the thread on a CMM. Optional air decay leak testing is available at assembly level.
Q3. Which stainless grade do you recommend?
AISI 304 suits general under-body conditions. AISI 316 is recommended for higher chloride exposure, and 17-4PH is chosen where higher strength and hardness are needed.
Q4. Can you supply mating components as a set?
Yes. We can produce the rack housing, end cap and related brackets as a matched set with common datum control across the parts.
Q5. What is your prototype capability?
We supply prototype end caps using rapid tooling or printed patterns, allowing bench and vehicle validation before production tooling is committed.
Q6. How do you pack and ship parts?
Parts are individually protected, packed in labelled cartons with heat lot and part number identification, and shipped with the inspection documentation you require for goods receipt.
