Thin Disc Flange Plate with Face Flatness 0.01mm and Bolt Circle PCD 0.05mm Verified by Free State Inspection

Thin flanges are machined with the release in mind, not just the cut. A disc 5 to 12 mm thick and 100 to 300 mm across bends under clamping force, machines flat while held, then springs back into a dish the moment the chuck opens. We control that by using light clamping on soft jaws or a vacuum chuck, removing equal stock from both faces, and finishing each side under the same load. Final flatness is measured with the part free and supported on three points, and bolt circles are checked on the CMM for pitch circle diameter and equal spacing.

• Quality system: ISO 9001:2015
• Materials: SS304 / 316L / 303, 6061 aluminium
• Process: stress relieved before finishing
• Track record: exporting since 2008

The hardest part of turning a thin flange is not the turning — it is the moment the chuck opens. A disc 5 to 12 mm thick and 100 to 300 mm across bends under clamping force, gets machined flat while held, and springs back into a dish the moment it is released. The inspector measures it on the bench, finds 0.05 mm of bow, and the flange then leaks, rocks on its mounting face, or pulls the mating part out of alignment when the bolts are tightened.

So we machine thin flanges with the release in mind: light clamping on soft jaws or a vacuum chuck, an even stock allowance removed from both faces, a finishing pass that takes the same load on each side, and a final check performed with the part free and supported on three points. Bolt circles are drilled and checked on the CMM for pitch circle diameter and equal spacing, because a hole pattern that is right in diameter but uneven in spacing still will not assemble.

• Material: SS304, SS316/316L, SS303, 17-4PH, 6061 and 7075 aluminium, brass C36000, engineering plastics on request.
• Geometry: flat disc, single or double step, spigot, centre bore or blind centre, raised sealing face, O-ring groove, lightening pockets, hex or spanner flats.
• Hole patterns: any bolt circle from 4 to 24 holes, through, tapped, counterbored or slotted; unequal spacing and clocked patterns supported.
• Finish: passivation per ASTM A967, anodising for aluminium, electropolish, bead blast, black oxide, nickel plating, as-machined.
• Size: diameter 20 mm to 400 mm, thickness 2 mm to 60 mm, bore up to 250 mm.
• Input: STEP, IGES, DXF, PDF drawing, or a sample flange we measure and re-model.

Flange drawings usually carry a bolt pattern, a sealing face and a part number that points straight at an assembly, which is why the file is treated as confidential from first contact. A mutual NDA is signed before any drawing is opened — ours in English or Chinese, or your own form — and a countersigned copy goes back before work starts. Only the project engineer, the lathe programmer and the cell supervisor have access, with the file in a restricted folder rather than the open shop network. The cell is camera free: no photographs for our catalogue or website, no customer part kept on display or reused as a sample, subcontracting only with 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, 200+ customers served, turnover in the RMB 10–20 million band. The plant runs CNC lathes, turn-mill combined centres with live tooling and sub-spindle, and 4-axis / 5-axis machining centres under an ISO 9001:2015 quality system, serving medical, robotics, automotive, aerospace, automation, laser, LED, lithium battery and precision instrument programs. Turning, bolt circle machining, passivation coordination and CMM inspection are all in our own plant in Dongguan.

Turned flanges and discs from this plant ship into ten sectors. The list is what customers order, not a marketing wish-list.

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 passivation and free-state inspection.
• Small batch 10–100 pcs: 7–14 working days.
• Repeat orders: released from archived program, soft jaws and hole pattern — flatness and PCD repeat to the same values.
• Capacity: 10,000 pieces per month across the plant.
• Visibility: a dated progress note with photos of your actual flanges at turning, drilling and inspection.
• Shipping: faces interleaved and protected, parts packed flat in foam-lined export cartons so a thin disc cannot bow in transit.
• Rush: weekly overtime slots held for line-down cases — give us the deadline and we confirm before the order.