17-4PH CNC Turning Heat Treated Jig Bushing and Flanged Knurled Bushing for Precision Press Fit Fixtures
Hardened Jig Bushing 17-4PH
,Ground Bore 0.01mm Fit
,Flange Press Fit Bushing
A hardened flanged knurled jig bushing manufactured from 17-4PH stainless steel, CNC turned, heat treated to H900 condition, and precision ground after hardening to hold an 0.01 mm bore tolerance. The knurled anti-rotation band and flange provide secure press-fit location in fixture plates, while the ground bore guides drills, reamers, and pins with repeatable accuracy.
- Bore tolerance 0.01 mm
- Ground after heat treatment
- H6 / H7 available
- Hardness HRC 40–47
- 17-4PH H900 condition
- Certificate included
- 1 piece minimum, no tooling charge
- ISO 9001:2015
Ground bore with knurled anti-rotation band. First article report with every shipment. Exporting since 2008.
A flanged knurled jig bushing does two jobs in a fixture: it locates a drill, reamer, or pin at a fixed position, and it refuses to rotate or walk out of the fixture plate. The knurl band pressed into the plate provides the anti-rotation grip; the flange sets the height; the bore guides the tool. If the bore is machined before hardening and never touched again, it moves — 17-4PH grows and distorts in the H900 age, typically enough to lose an H7 fit.
So the sequence here is deliberately different from a plain turned sleeve: turn with grind allowance, heat treat, then grind the bore and the flange face. Material removal happens after the metallurgy has finished moving, which is why an 0.01 mm bore fit survives, and why the bushing keeps that fit after thousands of drilling cycles.
| Step | Operation | Detail |
|---|---|---|
| 1 | Bar and material certificate | 17-4PH stainless bar, hardness condition recorded; SS440C or 52100 alternatives on request. |
| 2 | Turn first op | OD, flange, knurl blank and pre-bore with grinding allowance; datums prepared for the post-heat-treatment grind. |
| 3 | Knurl band | Straight knurl on the OD below the flange; crest diameter held so the press fit into the plate is repeatable. |
| 4 | Heat treatment | H900 age to HRC 40–47, in a controlled furnace with a signed hardness certificate for the batch. |
| 5 | Bore grinding | Internal grinding after HT to the drawing fit, roundness 0.005 mm, straightness and taper controlled along the guiding length. |
| 6 | Face and OD grind | Flange face ground square to the bore; seat face flatness held so the bushing sits down in the plate without rocking. |
| 7 | Deburr, mark, inspect | Laser marking of size or part number, final CMM check, first article report and hardness certificate with the shipment. |
| Feature | Held to | Verified by |
|---|---|---|
| Bore diameter (H6 / H7 / custom) | ±0.01 mm, roundness 0.005 mm | Bore gauge plus CMM, 100% on jig work |
| Bore taper along guiding length | 0.008 mm | CMM axial scan |
| Concentricity bore to OD | 0.01 mm | CMM on mandrel |
| Flange face squareness to bore | 0.01 mm | Granite plate plus indicator |
| Flange thickness and seat height | ±0.02 mm | Height gauge |
| Press-fit OD over knurl band | ±0.03 mm | Micrometer over crests |
| Hardness after heat treatment | HRC 40–47 (H900) | Rockwell tester, batch certificate |
| Bore surface roughness | Ra 0.4 µm ground | Roughness tester |
If your drawing calls for a standard jig bushing fit rather than a custom one, tell us the nominal and the standard you work to and we grind to that band; if the fixture plate bore is already cut, send its measured size and we will set interference to suit it rather than to a nominal.
- Configurations: plain bore, stepped bore, two-diameter guiding bore, counterbore for a tool shank, cross hole for a retaining pin, internal thread for a locking screw.
- Outside features: flange with or without knurl band, plain OD press fit, external thread with locknut, O-ring groove, shoulder seat.
- Anti-rotation options: straight knurl, diamond knurl, hex flats, keyway, dowel hole, or a combination of knurl plus flat.
- Materials: 17-4PH as standard; SS440C and 52100 for higher wear, 304 / 316L for corrosive fixtures, brass for non-marring locations.
- Hardness: HRC 40–47 standard on 17-4PH; HRC 58–62 available in 440C with matching grind allowance.
- Marking: bore size, part number, customer code or batch number laser marked on the flange edge.
- Reverse engineering: a worn bushing is measured, the model rebuilt and sent for approval before machining.
A jig bushing reveals fixture layout, hole patterns and tool sizes — information that describes a production process rather than just a part. We sign a mutual NDA before any file is opened, ours in English or Chinese or your own form, and return a countersigned copy before work starts. The drawing is visible only to the project engineer, the grinding specialist and the cell supervisor, held in a restricted folder rather than on the shop network. No photographs are taken of customer parts for our catalogue or website, customer parts are never used as display samples, no logo or program name appears in our marketing without written permission, subcontracting requires your written approval, and at program close drawings and inspection data are deleted or returned with written confirmation.
Dongguan Changxinda Precision Technology Co., Ltd has machined custom metal parts since 2008 — 15+ years, 90 to 100 staff, 50–60% of output exported to North America and Europe, more than 200 customers served, turnover in the RMB 10–20 million band. Turning, milling, heat treatment coordination, grinding and inspection are handled inside our own plant in Dongguan under an ISO 9001:2015 system, with 4-axis and 5-axis machining centres and turn-mill capacity supporting medical, robotics, automotive, aerospace, automation, laser, LED, lithium battery and precision instrument programs. You are dealing with the workshop, not an intermediary.
- Prototype: 5–10 working days where heat treatment is involved; 3–7 days for unhardened variants.
- Small batch 10–100 pcs: 10–18 working days including HT and grind.
- Repeat orders: released from archived programs, grind wheel setup and inspection plan — no re-programming.
- Capacity: 10,000 pieces per month across the plant.
- Visibility: dated progress note at turning, heat treatment and grinding, with photos of your actual parts.
- Shipping: oiled and individually bagged, foam-lined export carton, express or air and sea freight per your forwarder.
- Rush: express heat-treatment slots and weekend grinding are available; give us the date you must hit and we confirm before the order.
A: Because 17-4PH moves during the H900 age and the bore would end up outside an H7 band. Grinding after heat treatment removes the distortion and gives roundness of 0.005 mm along the guiding length — the property that actually determines whether a drill wanders. The extra step costs a little and saves scrapped fixtures.
A: On a bushing of this size, typically 0.02–0.05 mm of growth and a few microns of ovality depending on section thickness and how the part is fixtured in the furnace. We plan 0.15–0.25 mm of grind allowance on the bore and on the flange face, which absorbs it, and we verify actual movement on the first article of a new design.
A: For a hardened bushing in a steel plate, a light interference in the order of 0.01–0.02 mm on the knurl crest diameter usually holds without cracking the plate; in aluminium we go slightly larger and rely on the knurl teeth to bite. Send the measured plate bore and we set the crest diameter to it, and if the plate is thin we recommend a flanged version with the knurl band shortened.
A: Yes, because both are referenced to the same turned datum and the bore is ground after HT with the part held on that datum. Concentricity of 0.01 mm between bore and crest circle is our standard, and the flange face is ground square to the bore so the bushing seats without rocking.
A: One piece, no tooling charge. A hardened custom bushing typically ships in 5–10 working days after drawing approval, and a written quotation normally returns within 24 hours of receiving the drawing or model.
A: Yes, as standard. NDA is signed and countersigned before the file is opened, access is limited to the engineer, grinder and supervisor, no photos are taken of customer parts, and files are deleted or returned at program close on request.
Attach the drawing or model with the quantity and the date you need the parts, and you will get a quotation, the process route including heat treatment and grinding, and a firm delivery date. NDA paperwork can be handled in the same exchange.
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