Aluminum Cylinder Head Specification Example for City Buses: Sealed Unit
Aluminum Cylinder Head Specification Example for City Buses: Sealed Unit
This is a worked specification for aluminum cylinder head in a sealed unit programme. It is the document we would send a buyer who asks what exactly they are getting: the material, the dimensions that are actually controlled, the finish, and the checks that happen before anything is packed.
The sealed unit version exists because the duty cycle on city buses is not the same as on a showroom vehicle. Where the two are specified identically, something fails later — usually a fitment that looked right on paper and failed on the bench.
Example specification
| Item | Aluminum Cylinder Head |
|---|---|
| Application | City Buses |
| Version | Sealed Unit |
| Base material | Forged Aluminium |
| Controlled dimensions | 5 key dimensions, recorded per lot |
| Tolerance band | ±0.05 mm |
| Finish | zinc plated |
| MOQ | 200 pieces per specification |
| Sampling | 14 working days, 5 days per revision |
| Compliance | SGS |
How the example is built up
- Start from the duty cycle, not from the catalogue photograph.
- Fix the base material in writing — Forged Aluminium, in this example.
- List the dimensions that are actually controlled and the tolerance on each.
- Name the finish and what it has to survive.
- State the inspection level and who pays when a lot fails.
Processes involved
- shot blasting
- heat treatment
- rubber vulcanisation
- precision stamping
- electroplating
- die casting
Where this example applies
Programmes that run sealed unit most often specify this build for city buses. Related applications include off-road bikes, city buses, delivery vans, racing teams, courier fleets.
Checks before packing
- Dimensional report against the approved drawing.
- AQL 1.5 sampling on the finished lot.
- Finish inspection under agreed lighting.
- Carton drop test on the first lot of a new packing specification.
Questions buyers ask
How is packing specified?
Individual packing, inner box quantity and carton marking are confirmed at quotation stage so the cartons arrive ready for your warehouse.
How long does sampling take?
Samples leave the factory in 14 working days, and each revision round adds about 5 days once you have seen the first piece.
Can you match an existing sample?
Send a sample and we will reverse-engineer the specification, then produce a counter sample for approval before any bulk starts.
Can the specification be held on file?
Yes. Once approved, the specification is recorded against your part number so a reorder reproduces the SGS-compliant build instead of a fresh interpretation.
Send the part number, the annual volume and the target market, and we will come back with a specification and a sampling plan.
