CNC Machined Parts and Precision Components
Bushings, flanges, housings and non-standard precision parts machined to the drawing — turn-mill, cylindrical grinding, wire EDM, full-dimensional inspection.
Most custom gear enquiries arrive with more than a gear on the drawing. There is a housing the gear sits in, a flange the housing bolts to, a bushing that takes the wear, a shaft with a keyway or a spline. If those parts come from a different supplier, someone has to take responsibility for how they fit together.
PinyiGear machines those parts in the same workshop, to the same drawing set. This page covers what we make, how tolerances are handled, and what a drawing has to specify so the part comes out usable rather than merely dimensionally correct.
What we machine
- Bushings and sleeves — plain, flanged, with oil grooves or locating shoulders
- Flanges and covers — bolt patterns, spigots, sealing faces
- Housings and bearing seats — bored and faced in one setup where concentricity matters
- Locating pins and guide bushes — for fixtures and dies
- Non-standard precision parts — the parts that do not have a catalogue number
Dimensions, tolerances and accuracy grades come from the customer drawing. Where a drawing leaves something open — a corner radius, a chamfer, a general tolerance — that is a conversation before production, not after.
Process routes
| Process | Typical use | What it holds |
|---|---|---|
| CNC turning | Shafts, bushings, flanges of rotational form | Diameter, roundness, face squareness |
| CNC turn-mill | Parts needing turned features and milled features without re-chucking | Concentricity and position between features machined in one setup |
| Machining centre | Housings, plates, parts with multiple faces and hole patterns | Position tolerance across faces |
| Cylindrical grinding | Hardened shafts, bearing seats, precision bores | Finish, roundness, size in the tight bands |
| Surface grinding | Flat faces, spacers, plates | Flatness and thickness |
| Wire EDM | Hardened parts, internal profiles, sharp-cornered apertures | Profile accuracy after hardening |
The route is chosen by what the drawing asks for, not by what is convenient. A bearing seat called to h6 with a fine finish is a grinding job; the same seat with a general tolerance is a turning job, and quoting both at the same price would be wrong.
Tolerances: what to put on the drawing
General tolerances cover most of a part. The features that decide whether it works deserve their own callouts:
- Bearing seats and bores — size, roundness, cylindricality, surface finish
- Fits between mating parts — the fit class, not just the dimension
- Concentricity or runout between a bore and an outside diameter
- Position tolerance for hole patterns, referenced to a stated datum
- Squareness between a face and an axis
- Surface roughness on sealing and sliding surfaces
Where a drawing specifies only nominal dimensions and a block tolerance, parts can be made that meet the print and still not assemble. The datum scheme is what turns a set of dimensions into a functional part.
Materials
| Group | Grades we machine |
|---|---|
| Carbon and alloy steel | 45#, 40Cr, 42CrMo, 20CrMnTi, 38CrMoAl |
| Stainless steel | 304, 316, 420, 440C |
| Aluminium | 6061, 7075 |
| Copper alloy | Brass, bronze |
| Engineering plastics | POM, nylon, PTFE, PEEK |
Heat treatment — quench and temper, carburising, nitriding, induction hardening — is scheduled according to the drawing and to when the part still needs machining. Hardening before the last operations turns simple work into grinding work.
Surface treatment
Black oxide, zinc plating, chrome plating, anodising and Dacromet are all available, usually through qualified finishing partners with the finish specified on the drawing. Plating thickness and any masking requirements belong on the print: a chrome-plated bore changes size, and a masked thread is the difference between a part that fits and one that does not.
Inspection
Inspection follows the drawing, not a fixed sampling plan:
- Dimensions — calliper, micrometer, height gauge for general work
- CMM for position, profile and features referenced to datums
- Roundness and cylindricity on bearing seats and bores
- Surface roughness on sealing and sliding faces
- Hardness where heat treatment is specified
- Thread and spline gauges where the drawing calls for them
For repeat parts an inspection record travels with the batch, with the measured values against the drawing’s tolerances rather than a simple pass mark.
Standards referenced
Customer drawing first. Where the drawing is silent, the usual framework is GB/T 1804 for linear and angular tolerances, ISO 2768 for general tolerances, and GB/T 1800 for fits. Where a customer works to DIN or ANSI, the drawing governs.
Where these parts fit
Gearbox housings and covers, pump bodies and flanges, machine tool fixtures, die and mould components, automation brackets, sensor mounts, and the replacement parts that keep older equipment running when the original manufacturer no longer supplies them.
Working with a gear order
When housings, shafts and gears are made in the same shop, the fit between them stops being a negotiation between suppliers. A gear bore and a shaft journal that are dimensioned against the same drawing set can be machined and inspected as a pair, and if something does not assemble, there is one place to look.
What to send
- Part drawings (PDF, DXF, STEP, DWG, IGES) with datums, tolerances and surface finish
- Material and heat treatment, or the duty if these are open
- Surface treatment and any masking requirements
- Quantity and whether the part is a prototype, a first batch or repeat production
- Any mating part drawing, when the fit matters
Send a part drawing for quotation
FAQ
Can you hold ±0.005 mm? On the right features and the right process, yes — but the number only means something attached to a specific feature with a stated measuring method. Blanket tolerances across a whole part are usually not necessary and always cost money.
Do you make one-off parts? Yes. Prototype and repair parts are normal work here; the process route is the same, only the setup cost is spread over fewer pieces.
Can you reverse-engineer a part from a sample? Where the geometry can be measured, yes. Send the sample or a full set of dimensions; the drawing produced from it is confirmed before production.
Do you handle heat treatment and finishing? Yes, in-house where we have the process and through qualified partners where we do not. The specification stays on the customer drawing either way.
Can you supply the assembly rather than individual parts? Yes. When housing, shaft and gear are ordered together, they can be machined against one datum scheme and checked as a set.