0.008mm Face Flatness H7 Bearing Bore Square Base Bearing Seat by Single Setup Turn-Mill

This square base is a bearing seat: a bearing presses into the central bore, the shaft passes through, and the top face around the bore takes the axial load through the bearing shoulder. It is bolted down at the four corners, so the base has to sit flat on the frame while holding the bore square to that same face.

The numbers that matter are all related. A top face that is 0.02 mm out of flat pulls the base down unevenly when the corner bolts tighten, and the bore distorts with it. A shoulder that is not square to the bore seats the bearing on one edge, and the shaft runs with a runout that appears only after the machine is assembled.

1. Drawing and bearing review. We confirm bearing type and bore fit, shoulder width, pocket depth, seal groove section, corner hole pattern and load direction, then quote within one working day.
2. Material verification. 6061-T6 or 6082-T6 plate is checked for grade, temper and as-received flatness before cutting.
3. Stress relief and facing. The blank is stress relieved and the bottom face is faced flat, which becomes the datum for the pocket and the bore.
4. Turn-mill pocket. The circular pocket is machined to ±0.02 mm depth in the same setup as the bore, so the pocket floor and the bearing shoulder are cut from one reference.
5. Bearing bore. The bore is drilled, bored and reamed to H7 with 0.008 mm roundness, then checked with a bore gauge before the groove is cut.
6. Shoulder and seal groove. The bearing seating shoulder is faced square to 0.01 mm, and the O-ring groove is cut to ±0.03 mm in width and depth in a single pass.
7. Corner holes and finishing. Corner mounting holes and any dowel holes are drilled with live tooling at ±0.02 mm position, then edges are broken and the part is masked for black anodizing.
8. Inspection. CMM for face flatness, bore perpendicularity and shoulder squareness, bore gauge for diameter and roundness, groove pin gauge, then a first article report with the batch.

Buyers often specify the bore and stop there, but a bearing seat is a system of three features that have to agree: the bore diameter holds the outer ring, the shoulder squareness positions the ring axially, and the face flatness keeps the housing from distorting when it is bolted down. Get the bore right and the other two wrong, and the bearing still runs tight, hot and noisy.

That is why we cut the pocket, bore and shoulder in a single setup, then check them against the same datum. The seal groove is cut after the bore so the groove does not interrupt the boring pass, and it is masked during anodizing because 20 microns of coating on the groove floor changes the O-ring compression.

Base size, pocket diameter and depth, bore fit, shoulder width, groove section, corner hole pattern, material and coating are all built to your drawing. One piece is a normal order with no tooling charge and no setup fee, and the prototype follows the same inspection plan as production. If the shoulder is too narrow for the bearing you specified, our engineer raises it before machining.

• NDA before files. Mutual non-disclosure is signed before drawings or samples are released.
• No public reference. Confidential bases never appear in samples, catalogues, website photos or trade fairs.
• Separated cell. Sensitive work runs with named operators and project-coded programmes.
• Partner control. Anodizing suppliers receive process specifications only.

Dongguan Changxinda Precision Technology Co., Ltd has produced custom machined parts since 2008, with turn-mill centres, CNC lathes with live tooling and four-axis and five-axis machining centres on site. The company employs 90 to 102 people, holds ISO 9001:2015 certification, serves more than 200 customers, exports 50 to 60 percent of output and records annual sales of USD 10 to 20 million.

• Confirmed dates. Prototypes 4 to 8 working days, batch orders 14 to 22 working days after drawing approval.
• Repeat orders skip setup. Programmes, fixtures and gauge sets stay on file.
• Reserved machine time. Blanket orders are scheduled into fixed monthly slots.
• Early warning. If material, anodizing or capacity threatens the date, you hear it before it is missed.
• Dispatch evidence. Photos, inspection report and packing list before shipment.

Each base is bagged with desiccant, seated in a foam tray so the bore shoulder and seal groove are protected, then sealed in a moisture barrier bag. Trays fit a five-layer export carton marked with part number, quantity and batch code. Sea freight ships on fumigation-free plywood pallets; neutral cartons are available.