L-Type Robot Joint Housing Confidential Build Circular Bearing Seat 0.01mm

Some robot joint parts cannot be shown. A joint housing carries the customer's kinematics, the bearing fit that sets repeatability, and the frame interface that no competitor should see. Buyers in this position do not need another supplier who posts their geometry in a gallery; they need a machine shop that can be trusted with the drawing and can still hold 0.01 mm.

Dongguan Changxinda Precision Technology Co., Ltd. has run confidential build to print work since 2008. The company employs more than 90 people, operates 4-axis and 5-axis machining centers, turn-mill combined lathes and precision CNC lathes, holds ISO 9001:2015, and exports 50 to 60 percent of production to robot, automation and medical buyers. Confidential programs are handled on a separate job track with named staff and restricted documentation.

What Confidentiality Covers Here

Confidentiality is a process, not a promise in an email. For this part family the following controls are standard, and additional terms can be written into the agreement.

• Mutual NDA before drawings move. We sign the customer's NDA or provide our own, whichever the customer's legal team prefers.
• Drawing custody: files are held on a restricted folder with named access, not on a shared drive, and are not forwarded to any third party for quoting.
• No published geometry: confidential parts are never used in our gallery, news, blog or social content, and no photographs of the part are taken for marketing.
• Sub supplier restriction: heat treatment and surface finishing, when required, go only to suppliers bound by the same terms, and the parts travel without customer part numbers visible.
• Marking discipline: laser marking is limited to what the customer specifies, and neutral marking can be used when the part number itself is sensitive.
• Program ownership: CNC programs and fixtures built for a confidential part remain exclusive to that customer and are not reused on other work.
• Sample return and scrap control: rejected parts and samples are returned or destroyed on instruction, with a written record.

The Part: L-Type Housing With a Circular Bearing Seat

The geometry is an L shaped body: a square base that bolts to the arm or the frame, and a perpendicular housing bore that carries the bearing or the reducer output. The square base gives a stable mounting plane; the circular seat gives the rotation. Both have to be right, and they have to be right relative to each other, which is where most of the difficulty sits.

Process Route: Base First, Bore Last

The order of operations is what makes the two features agree. Cutting the bore first and then the base means the base is machined on a part that has already moved.

Precision Declared for This Family

• Bearing seat bore diameter and roundness 0.01 mm, measured at three depths to catch taper
• Bore to base squareness 0.01 mm over the bore length, measured on the CMM with the base clamped as in service
• Base flatness 0.01 mm, base squareness 0.01 mm over 200 mm
• Dowel hole true position 0.01 mm and bore to dowel centre distance 0.01 mm
• Bearing seat surface roughness Ra 0.8, with a trace supplied on request
• Wall thickness checked at eight points; uneven wall is the main source of thermal drift in a joint
• Metrology room at 20 degrees Celsius, CMM resolution 0.001 mm, first article report with a ballooned drawing

Non Standard Customization

• Base from 50 x 50 mm to 300 x 300 mm, bore from 20 mm to 200 mm, L height to the customer frame
• Materials: 6061-T6 and 7075-T6 aluminum, 304 and 316L stainless, 40Cr for the loaded seat
• Finishes: clear, black and hard anodizing, chromate free conversion coating, nickel plating, with bearing surfaces masked
• Weight reduction pockets and ribs placed to the customer's stiffness target rather than by rule of thumb
• Interface patterns matched to your reducer or bearing supplier, including dowel and clearance hole combinations
• Neutral marking, customer marking or no marking, according to the confidentiality instruction
• Drawing input in STEP, IGES, X_T, DWG, DXF or PDF through the agreed secure channel
• Prototype quantity from one piece, with design feedback returned within 24 hours

Delivery Stability

A joint housing on the critical path of a robot build cannot be late, and confidentiality does not change that. Scheduling is quoted from the process route, and the route is proven on the prototype.

• Prototype part: 5 to 8 working days including first article inspection
• Batch of 10 to 100 pieces: 10 to 18 working days including anodizing
• Recurring releases: reserved machine capacity with a fixed weekly slot and the same fixture and program
• A named project engineer per account, weekly status update without photographs when the part is confidential
• Written notice at least 5 working days before the ship date if any step is at risk
• Buffer stock of one release quantity held at the plant on instruction, released on call
• Shipping with neutral packing and neutral documentation when the program requires it

Questions From Robot Builders

Will you sign our NDA, and does it cover sub suppliers?

Yes. We sign the customer's NDA before drawings are transferred, and we extend equivalent terms to any heat treatment or finishing supplier used on the job. If your NDA has specific clauses on sub suppliers, send it and we will confirm in writing.

Can we visit the plant before releasing a confidential drawing?

Yes, and for confidential programs we encourage it. A visit can be arranged without seeing other customers' parts, and the areas used for your job can be shown in advance.

How do you keep the geometry out of your marketing?

Confidential parts are excluded from the gallery, news, blog and social content, and no marketing photographs are taken. If a customer later allows an anonymised image, it is released only with written approval.

What happens to the fixtures and programs if we move production?

They belong to the customer's program. On request we ship the fixtures, hand over the programs and the inspection plan, and provide a transition document so the next supplier starts from a known process rather than from the drawing alone.