Wexmar provides custom spacer machining for OEMs that need bearing spacers, shaft spacers, sleeves, shims, washers and precision rings built to print. From our shop in Canastota, New York, we produce CNC machined spacers on Swiss-type machines and CNC lathes, with in-house surface and centerless grinding when the faces or diameters need it.
What spacers do and who buys them
A spacer sets the distance between two parts. On a shaft, it controls the axial position of bearings, gears and pulleys. In a bearing stack, matched inner and outer spacers set preload. Under a fastener, it fills a gap or raises a component. Because a spacer's length and face parallelism translate directly into assembly stack-up, precision spacers are often held tighter than the parts around them. Buyers include power transmission and bearing companies, pump and spindle builders, machine tool and automation OEMs, instrumentation and medical hardware suppliers, and aerospace and defense build-to-print programs.
How we machine CNC spacers
Small spacers up to 32 mm diameter are run on our four Maier MLK-32 Swiss-type machines with FMB bar feeders. The Swiss machine drills, bores, turns and parts off in one cycle, then faces the back side on the sub-spindle, which keeps both faces square to the bore. Production quantities can run lights-out. See Swiss machining.
Larger spacers, sleeves and rings are turned on our Mazak and Doosan CNC lathes, including the Nexus QT200, Nexus 250, Nexus 450-II and Multiplex 6300Y twin-spindle machine. Tube or cored stock reduces waste on large-bore spacers. When the drawing requires face parallelism or length tolerance beyond what turning reliably holds, we finish both faces on our surface grinder. ODs that need tenths are finished on our centerless grinder. See CNC turning.
Spacer materials
- Steel: 1018, 12L14, 4140 and 52100 for hardened bearing spacers.
- Stainless: 303, 304, 316, 416, 440C and 17-4 PH.
- Aluminum: 6061-T6 and 7075 for lightweight spacers.
- Brass and bronze: for conductive or non-sparking service.
- Plastics: acetal, nylon, PTFE, PEEK and UHMW for isolation and light loads.
- Others: titanium and high-nickel alloys.
Critical spacer features and how we hold them
- Length (thickness): faced on both sides in one cycle or ground to a tight band for stack-up control.
- Face parallelism: surface ground when the drawing calls for parallelism in tenths, which is common on bearing preload spacers.
- Face perpendicularity to bore: both faces cut in the same chucking as the bore on the Swiss or twin-spindle lathe.
- Bore fit: bored or reamed for slip fit over a shaft, held to H7 or better where needed.
- Matched sets: inner and outer spacers ground together to equal length when used for bearing preload.
Typical tolerances and finishes
| Feature | Typical tolerance | Tighter on request |
|---|---|---|
| Length / thickness (turned) | ±0.002 in | ±0.0005 in |
| Length / thickness (ground) | ±0.0005 in | ±0.0001 in |
| Face parallelism | 0.001 in | 0.0001 in (ground) |
| Bore diameter | ±0.001 in | ±0.0003 in |
| OD | ±0.001 in | ±0.0002 in (ground) |
| Face finish | 32 Ra | 8 Ra (ground) |
These are typical values. Thin spacers and plastic spacers deflect under clamping, so we review those tolerances with you before quoting.
Secondary operations
Heat treat, black oxide, zinc and nickel plating, anodizing and passivation are performed through qualified outside processors. Hardened spacers are ground after heat treat on our in-house grinders so final length and parallelism are held in the hardened state.
Quantity patterns
Spacers are ordered in every quantity: matched sets of 2 or 4 for a spindle rebuild, production lots of 500 to 5,000 for OEM assemblies, and blanket orders released monthly. Swiss lights-out running and batch surface grinding keep costs in line at volume.
Inspection
Thickness and parallelism are measured with calibrated micrometers, gage blocks and indicators on a surface plate. Bores are checked with bore gages and pin gages, and profiles on our Mitsubishi optical comparator. Matched sets are measured and tagged together. AS9102-format first articles, material certs and lot traceability are available. See inspection and quality.
Getting a quote
Send a drawing with thickness tolerance, parallelism, material and quantity. You can upload a drawing for an instant estimate, and an estimator will confirm pricing. Or call (315) 400-2654. Related: standoffs and bushings.