CNC Turn-Milled Stainless Steel Sleeve Set
Sleeves and caps turn-milled from 304 stainless, with a H8 bore round within 0.01 mm, outside-to-bore runout of 0.02 mm, cross holes at 90° ±0.1° and every breakthrough back-chamfered 0.3 mm so the bore stays clear.
- Bore H8, 0.01 mm Round
- Cross Holes at 90° ±0.1°
- Wall Runout 0.02 mm
- Deburred Inside the Bore
*Send the shaft fit and the position of the cross hole relative to the key or flat. A hole 0.5 mm off the datum will not line up with the pin, and the sleeve has to come off to be re-drilled.
Turn-Milled Sleeve Overview
A sleeve with cross holes is a bearing surface and a pin location at the same time. The bore sets the fit on the shaft, the holes set the angular position, and a burr at either one ruins the assembly.
The sleeve is turned and bored in one clamping, the cross holes are milled on a sub-spindle with the part still held, and each breakthrough is back-chamfered before the part is parted off.
304 Stainless
304 resists washdown and does not mark a stainless shaft. It work-hardens at the cross hole edge during drilling, which is why the breakthrough is chamfered rather than reamed.
316L or 303
316L is used in chloride service, and 303 where the sleeve is drilled with many small cross holes and the free-machining grade saves a deburring operation.
A 2 mm wall at a cross hole is the minimum; below that the hole pulls the bore oval by 0.01 mm and the sleeve will not pass over the shaft after drilling.
Turn-Milled Sleeve Specifications
Turning, cross milling and deburring data for sleeves, with the bore and angular values that keep an assembly sliding.
| Specification | Machining Data | Specification | Machining Data |
|---|---|---|---|
| Product | Turn-Milled Sleeve and Cap Set | Machining Process | CNC Turning, Cross Milling, Deburring |
| Material | 304 Stainless | Envelope | Ø 12 – 60 mm OD, 20 – 120 mm Long |
| Bore | H8, Roundness 0.01 mm | Bore Finish | Ra 0.8 µm, Honed on Request |
| Wall Runout | 0.02 mm Outside to Bore | Wall Thickness | 2 mm Minimum |
| Cross Holes | Ø 3 – 8 mm, Angular Position ±0.1° | Hole Breakthrough | Back-Chamfered 0.3 mm |
| End Faces | Square to the Bore Within 0.02 mm | Chamfer | 0.5 × 45° Both Ends |
| Weight | 20 – 320 g per Piece | Coating | Passivated, Electropolished on Request |
| Customization | Hole Pattern, Groove, Flat, Set Quantity, Laser Mark | Lead Time | 6 – 8 Days Sample, 12 – 18 Days Batch |
| Inspection | Bore Air Gauge, CMM Hole Angle, Bore Scope on Breakthroughs | Packing | Bore Plug, Bagged by Piece Number |
Key Features of Our Sleeves
Bored and cross drilled without re-clamping, back-chamfered breakthroughs, degaussed and cleaned.
Cross Holes Without Re-clamping
The holes are milled on the same spindle as the bore, so the angular position stays within 0.1° and the hole axes intersect the bore centre instead of being offset.
Breakthrough Back-Chamfered
A back-chamfer tool cuts the burr from inside the bore after the hole breaks through; a hand deburr from outside leaves a lip that scores the shaft on assembly.
End Faces Square to the Bore
Both ends are faced square within 0.02 mm, so the sleeve sits flat against a shoulder and does not cock when the retaining screw is tightened.
Ultrasonically Cleaned
Cross holes trap swarf that air blow cannot remove, so the parts are ultrasonically cleaned and bore scoped before packing.
Sleeve that must slide without scoring?
Finishes for Turn-Milled Sleeves
The bore is a sliding surface, the outside is handled, the holes are a location.
| Finish | Main Purpose | Finish | Main Purpose |
|---|---|---|---|
| Passivation | Removes free iron after cross drilling | Electropolishing | Ra 0.4 µm in a hygienic bore |
| Bead Blasting | Even matte on the outside | Masked Bore | Bore stays H8 |
| Pickling | Removes heat tint if the cap is welded | Laser Marking | Angular position of the cross hole |
| Ultrasonic Clean | Removes swarf from the cross holes | Bore Plug | Keeps grit out in transit |
| Dye Penetrant | Checks for cracks at the hole edge | Assembly Trial | Sleeve fitted to its cap |
| Salt Spray | 500 h on 304 | Bore Recheck | H8 After Passivation |
*Electropolishing opens the bore by 5 to 8 µm and rounds the cross hole edge slightly; on an H8 sliding fit the bore is masked or polished before the final hone.
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Machining a Turn-Milled Sleeve
The cross holes are milled on the turned axis and back-chamfered from inside, so the sleeve slides over a shaft without scoring it at the hole edge.
01. Shaft and Pin Review
Confirm the shaft diameter, the pin position and the wall thickness, then decide the order of boring and cross drilling.
02. Turn and Bore
Turn the OD, bore to H8 with a boring bar, face both ends square and part off with enough stock for the second face.
03. Cross Mill
Mill the cross holes on the sub-spindle with the sleeve still in the collet, using the part datum rather than a vice stop so the angle holds to 0.1°.
04. Back-Chamfer and Deburr
Back-chamfer each breakthrough 0.3 mm from inside, break the outer edge 0.3 mm and check the bore with an air gauge.
05. Clean, Passivate, Pack
Ultrasonically clean, bore scope each hole, passivate, plug the bore and bag each piece with its number.
Send the shaft fit and the pin layout, and we will quote a sleeve bored and cross drilled in one clamping with every breakthrough deburred.
Turn-Milled Sleeve FAQs
Yes, any angle that the sub-spindle can index to, within ±0.1°. Non-orthogonal holes need a 4-axis set-up and a slightly longer lead time.
With a back-chamfer tool that enters through the bore and cuts the burr from the inside edge. It is the only way to remove the lip that forms where the drill exits.
H8 with 0.01 mm roundness, or H7 on request. H7 needs a hone after boring, because a boring bar alone leaves 0.015 mm of taper in a 60 mm sleeve.
By up to 0.01 mm on the bore if the wall is under 2 mm. At 2 mm and above the bore stays within tolerance and only needs a light hone.
Yes, and it is the reliable way to buy a sliding pair: the shaft is ground to the sleeve bore with 0.01 to 0.02 mm clearance, checked as an assembly.
Each piece is laser marked with its position number and the hole orientation, so a set can be fitted in the right order without measuring on the machine.
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