Clearance 0.005mm Interchangeable Matched Pin and Sleeve Set by CNC Turning for Precision Fitted Pin and Sleeve Pair Assembly

• Pair clearance: 0.005–0.010 mm; each pair fitted, then numbered
• Interchangeability: verified across the set — random re-pairing must still fit
• Order size: 1 set; prototypes in 3–7 working days
• Materials: SS304 / 316L / 420, hardened 440C
• Finish: ultrasonic cleaned and bagged as pairs
• Quality system: ISO 9001:2015; exporting since 2008

A pin and its sleeve are usually drawn with independent tolerances: the pin at h6, the sleeve bore at H7. Both can be perfectly in tolerance and the pair can still be wrong — a pin at the top of its band in a bore at the bottom of its band gives a clearance so tight the pair galls on assembly, and the reverse gives a pair with visible play. A customer who assembles from two bins of in-tolerance parts discovers this on the line, not on the drawing.

So we build the pair as a pair: the bore is measured, the pin is turned to that measured bore with the clearance you specify, each pair is trial fitted, and the pair is numbered and bagged together. We also test interchangeability, because a set that only works as matched pairs is useless if one pin is lost and replaced from stock — random re-pairing within the batch is checked and the result reported.

Interchangeability is listed as a tolerance because it is the property that decides whether a matched set is usable in production. A set where only the numbered pairs fit is a set that stops the line the day a pin is dropped.

• Pairs: pin and sleeve, pin and bush, plunger and guide, spool and body, roller and axle, gauge pin and setting ring.
• Material: SS304, SS316L, SS420, SS440C, 17-4PH, brass C36000, aluminium 6061, PEEK, POM, ceramic on request.
• Fit classes: slip fit, close running fit, press fit, or a clearance value you specify in microns.
• Finish: as-turned, polished Ra 0.2, passivation, electropolish, hard chrome, DLC, PTFE coating for dry running.
• Set options: numbered pairs, laser marked, colour coded, supplied in a fitted case or tray.
• Size: pin diameter 1 mm to 30 mm, sleeve bore 1 mm to 40 mm, length 3 mm to 200 mm.
• Input: STEP, IGES, DXF, PDF drawing, or a sample pair we measure and re-model.

A matched pair drawing reveals a clearance, a wear couple and a function — whether it is a spool in a valve body or a gauge pin in a setting ring. We sign a mutual NDA before any file is opened, in English or Chinese or on your own form, and return a countersigned copy before work starts. Access is limited to the project engineer, the lathe programmer and the cell supervisor, with the file in a restricted folder rather than the open shop network. No photographs of customer parts are taken for our catalogue or website, customer parts are never displayed or reused as samples, subcontracting requires your written approval, and at program close files and inspection data are deleted or returned with written confirmation.

Dongguan Changxinda Precision Technology Co., Ltd has been machining custom parts since 2008: 15+ years, 90 to 100 staff, 50–60% exported to North America and Europe, 200+ customers served, turnover in the RMB 10–20 million band. The floor holds CNC lathes, turn-mill combined centres with live tooling and sub-spindle, and 4-axis / 5-axis machining centres under an ISO 9001:2015 system, producing parts for medical, robotics, automotive, aerospace, automation, laser, LED, lithium battery and precision instrument programs. Turning, hardening coordination, pairing, ultrasonic cleaning and CMM inspection are managed in our own plant in Dongguan.

Matched pairs and turned sets from this plant ship into ten industries. Each line is a category we machine regularly, with the parts customers actually order.

All ten sectors run through the same plant and the same ISO 9001:2015 inspection discipline — only the material, finish and documentation package change.

• Prototype: 3–7 working days after drawing approval, including pairing and cleaning.
• Small batch 100–1,000 pairs: 10–16 working days.
• Repeat orders: run from archived programs and bore records; clearance repeats to the same band because pins are sized from measured bores, not from nominal.
• Capacity: 10,000 pieces per month across the plant.
• Visibility: a dated progress note with photographs of your actual pairs at turning, fitting and cleaning.
• Shipping: pairs bagged together and numbered, set packed in a tray so pins and sleeves cannot mix in transit.
• Rush: pairing and cleaning slots held weekly; tell us the deadline and we confirm before you order.