CNC Milled Aluminum Robot Joint Adapter Plate
CNC milled aluminium adapter plates that join a robot wrist to an end effector, a gripper or a vision mount, with a turned register on each side, bolt circles positioned within ±0.02 mm and faces flat to 0.02 mm. Lightening pockets are cut between the bolt groups, not through them.
- Register Turned to h7
- Bolt Circle ±0.02 mm
- Flatness 0.02 mm
- Both Interfaces in One Set-Up
*Send both interface drawings with the tool centre point marked. The register and the bolt circle on each side have to be machined from one datum, or the TCP moves every time the plate is changed.
Robot Joint Adapter Plate Overview
An adapter plate is a tolerance translator: it takes one bolt pattern and register and reproduces another. Everything that matters happens between the two faces, so the plate is machined from one datum and both registers are cut in the same set-up rather than flipped and re-clamped.
The plate is faced on both sides, the registers are bored, and the two bolt circles are drilled from the same centre. Lightening pockets are placed between bolt groups so the plate loses weight without reducing the clamp area under the bolt heads.
6061-T6 Aluminium Plate
6061-T6 is used because an adapter plate should be light and stiff, and it holds a bored register without springing when the tooling is bolted down. It anodizes to a uniform colour, which helps when several adapters belong to one cell.
7075-T6 for High Moment Loads
7075-T6 is specified when the end effector is heavy or offset, where the plate has to resist bending between the two bolt circles. It holds the register round at higher bolt torque.
Plate thickness follows the offset load, not the robot payload. A 10 mm plate is fine for a centred gripper and marginal for a 300 mm cantilever, whatever the payload rating says.
Robot Adapter Plate Specifications
Milling and boring data for adapter plates, with the register, bolt circle and flatness values that keep the tool centre point fixed.
| Specification | Machining Data | Specification | Machining Data |
|---|---|---|---|
| Product | Robot Joint / End Effector Adapter Plate | Machining Process | CNC Milling, Register Boring, Face Milling |
| Material | 6061-T6 Aluminium Plate | Register Diameter | h7 (0 / −0.021 on 40 mm) |
| Thickness | 6 – 30 mm | Bolt Circle Position | ±0.02 mm on Both Interfaces |
| Envelope | 50 × 50 mm to 300 × 300 mm | Face Flatness | 0.02 mm Across the Plate |
| Register Height | 2 – 8 mm Each Side | Parallelism of Faces | 0.02 mm |
| Bolt Sizes | M3 to M12, Through, Tapped or Counterbored | Register to Bolt Circle | 0.015 mm Concentricity |
| Lightening | Pockets Between Bolt Groups | Surface Finish | Ra 1.6 µm Registers, Ra 3.2 µm Faces |
| Customization | Register Step, Bolt Pattern, Cable Cut-Out, Marking | Lead Time | 6 – 9 Days (Sample), 12 – 16 Days (Batch) |
| Inspection | CMM Both Interfaces, Flatness, Register Gauge | Packing | Foam Interleaved, Bagged, Carton |
Key Features of Our Adapter Plates
One datum, two interfaces, no shift when the tooling is swapped.
Both Interfaces From One Datum
The two registers and both bolt circles are cut without re-clamping, so the relative position of the interfaces is held by the machine rather than by a fixture.
Registers Bored, Not Interpolated
Each register is bored with a single-point tool, staying round within 0.01 mm so the tooling seats on the face instead of rocking on the register.
Pockets Away From Bolt Groups
Lightening pockets are kept clear of the clamp area under each bolt head, so removing weight does not reduce the preload the joint can carry.
Orientation Marks Machined In
An index mark is cut into the edge on the same set-up, so the plate can only be fitted the way it was machined and programmed.
Need an adapter that keeps the TCP fixed?
Surface Finishes for Robot Adapter Plates
The registers are fit surfaces, so the coating is either kept out of them or the bore is sized after anodizing.
| Finish | Main Purpose | Finish | Main Purpose |
|---|---|---|---|
| Type II Anodizing | Colour coding and corrosion protection on the plate | Hard Anodizing | Wear face where tooling is repeatedly bolted and removed |
| Bead Blasting | Matte finish so the dye reads uniform across the plate | Masked Anodizing | Bare register where a press fit is specified |
| Laser Marking | Tool number and interface orientation on the edge | Chromate Conversion | Conductive finish for grounded tooling |
*Anodizing adds 7 to 10 µm per surface. Registers that locate a tool are masked, or bored 0.02 mm oversize and finished after the dye so the fit is unchanged.
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Milling Process for Robot Adapter Plates
Both interfaces are machined from one datum, so the tool centre point does not shift when the adapter is swapped.
01. Interface and TCP Review
Check both bolt patterns, both registers and the tool centre point on the drawings, and confirm which face is the datum before programming.
02. Plate Prep and Facing
Square the plate, face both sides to release stress, then re-face the datum side and mark it so every feature is cut from that surface.
03. Bore, Drill and Pocket
Bore the register, drill and tap both bolt circles from the same centre, then cut the lightening pockets between the bolt groups.
04. Flip and Second Register
Flip the plate on the machined face, bore the second register and drill its bolt circle from the same datum, then break all edges by 0.3 mm.
05. Anodize, CMM and Pack
Mask the registers if required, anodize to colour, measure both interfaces on a CMM, then pack with foam so the faces do not rub.
Send both interface drawings with the TCP marked, and we will quote the plate with both registers and bolt circles defined.
Robot Adapter Plate FAQs
Nothing measurable if both interfaces are cut from one datum: the relative position is held to ±0.02 mm. A plate machined in two set-ups typically adds 0.05 to 0.1 mm, which is enough to need a TCP re-teach.
Yes. Any pattern up to twelve holes per side is drilled from the same centre, and slotted holes are available where the two interfaces are not perfectly aligned in service.
6 mm for a small gripper interface, and 10 to 12 mm for a tooling plate over 150 mm across. Thinner plates deflect between bolt groups, which shows up as a rocking tool.
Yes. Dowel holes are reamed to H7 and positioned with the bolt circle, and they are the preferred alignment feature when the tool has to be refitted without re-teaching.
It adds about 0.01 mm per side. Registers that locate the tool are masked, and when the fit is critical the bore is finished after anodizing and checked with a plug gauge.
Six to nine days for a sample pair including programming, machining, anodizing and CMM. Batches of 20 to 100 pieces run twelve to sixteen days depending on the number of colours and masking points.
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