POM bushings and sleeves
We turn POM bushings and sleeves to the bore, outside diameter and shoulder dimensions on your drawing. The housing fit, running clearance and lubrication conditions define the mating arrangement.
POM parts for guides, bushings and moving assemblies
6 part examples
Acetal gears and drive components
An acetal gear combines the tooth form, module or pitch and pressure angle with its bore and hub. The quote identifies the gear-cutting method, tooth inspection and production responsibility.
POM guide blocks and slide components
We mill guide blocks with running faces, locating holes and mounting features. Counterface material and travel define the sliding contact; the drawing locates it relative to the assembly.
Acetal spacers and support rings
Spacers and support rings locate an assembly through their bore and load-bearing faces. Roller or wheel variants also depend on the running diameter, hub arrangement and specified runout.
POM wear pads and mounting blocks
Machined wear pads combine working contact faces with recessed fasteners and protected clearances. Load and cleaning conditions guide the specified POM grade and replacement requirements.
Acetal valve and manifold blocks
Acetal valve and manifold blocks combine internal passages, port threads and sealing faces. The agreed scope identifies the fluid-contact requirements and any separate pressure or leak test.
POM-C, POM-H and specialty acetal grades
POM-C: acetal copolymer
POM-C offers low moisture uptake and good machinability. It generally resists alkaline media and hydrolysis better than POM-H, which can matter when cleaning exposure takes priority over higher stiffness.[1]
- Include with your drawing
- Exact stock grade, supplier, color, fluid exposure and required records.
POM-H: acetal homopolymer
Consider the homopolymer when stiffness, strength and repeated loading matter. Delrin® is a branded acetal homopolymer, not a generic name for every POM material. [1] [2]
- Include with your drawing
- Approved material designation and whether a named Delrin® grade is mandatory.
Wear-modified POM for sliding contact
Lubricated acetal formulations can change friction and wear behavior. Compare the exact formulation for the load, speed, lubricant and mating surface, not only its color. [4]
- Include with your drawing
- Wear-grade designation, counterface, duty cycle and sample-test requirements.
Specialty POM for a defined requirement
A requirement for static dissipation, detection or a particular declaration needs a named grade and an agreed verification method. Select the requirement first; approve the exact material before an order.
- Include with your drawing
- Property limits, test method, approved supplier and permitted substitutions.
Delrin® grade and brand requirements
POM is also called acetal or polyoxymethylene. A request for generic POM, a request for POM-H and a request for a named Delrin® stock grade are not the same specification. Send the approved designation and state whether alternatives may be proposed. Color alone does not confirm the resin, additives or electrical properties. [1] [2]
Material choices are for review, not a live stock list or a claim that manufacturers’ grades are equivalent. Availability and the approved source are confirmed for each order.
| Property | POM-C TECAFORM AH natural | POM-H TECAFORM AD natural | Test condition |
|---|---|---|---|
| Density (g/cm³) | 1.41 | 1.43 | — |
| Tensile strength (MPa) | 67 | 79 | 50 mm/min |
| Tensile modulus (MPa) | 2,800 | 3,400 | 1 mm/min |
| Hardness (Shore D) | 82 | 85 | Shore D |
| Thermal expansion (×10⁻⁵/K) | 13 | 12 | 23–60°C, longitudinal |
| Water absorption (%) | 0.05 / 0.10 | 0.05 / 0.10 | 24 h / 96 h at 23°C |
| Melting temperature (°C) | 166 | 182 | DIN EN ISO 11357 |
Typical properties of the named unfilled stock grades; finished-part dimensions follow the drawing.
CNC milling and turning for acetal components
CNC milling for slots, pockets and locating holes
Working faces, hole relationships, internal corners and tool access define milled guides, fixtures and valve blocks. Blank support also affects the machining plan.
CNC turning for bores, shoulders and running diameters
For sleeves, spacers and roller blanks, show which diameters locate the part and which surfaces run against another component. Include bore finish, shoulder location and whether the fit will be checked loose or installed.
Workholding and Dimensional Stability
Acetal still needs plastic-specific workholding. Sharp tools, control of machining heat and suitable clamping help protect the surface and final dimensions. Stock form and the amount of material removed belong in the process review. [3]
POM dimensions and fits
Select a condition to add it to your POM parts brief.
| Feature | Specification | Acceptance condition | Verification |
|---|---|---|---|
| Bores and running diameters | Size limits; shaft/bearing arrangement; running clearance | Specified temperature; free-state or installed fit | Dimensional measurement; assembly trial where specified |
| Flat and guide faces | Datums; flatness or parallelism | Defined support; no forced flattening | Surface measurements; recorded support arrangement |
| Threads and inserts | Thread designation; depth; mating fastener | Specified insert and installation torque | Thread check; separate installation and position checks |
| Sliding and sealing faces | Roughness; measurement locations; edges; permitted marks | Functional surfaces identified | Separate appearance, roughness, sealing and running checks |
POM tolerances are confirmed against the actual part
POM tolerance review covers feature size, material grade and geometry. Mark the critical dimensions so the machining route and inspection scope match the drawing.
Fits and Assembly Features
Load, speed and counterface for sliding parts
Share the mating material, surface finish, load, travel or speed, lubricant and expected life. Where performance is important, agree a sample test rather than treating a material datasheet as a prediction for the assembly.
Support for thin walls
Mark the surfaces that can be held, and avoid leaving critical dimensions dependent on an unsupported lip. For uneven sections, ask whether rough machining and a stabilization step should precede final machining.
Cleaning and Operating Conditions
Chemical compatibility depends on the exact grade, agent concentration, temperature, contact time and mechanical load. We assess the operating fluid and cleaning cycle together, and confirm suitability for that particular chemical or hot-water duty.[1]
Keep fastening and bonding requirements explicit
Show screw engagement, inserts, press fits or the proposed bonding method. Provide assembly loads and any required trial, especially where a connection must be taken apart repeatedly.
POM replacement parts and assembly checks
Replacement limits
A worn guide, pad or bushing shows where material has been lost, not the target size of its replacement. We use the released drawing to separate the new working dimensions from the dimensions measured on the old part.
Fit and motion
When the shaft or housing stays in service, its retained dimensions determine the new bushing’s mating fit. We distinguish those interfaces from the worn bore or outside diameter of the removed part so the replacement restores the intended clearance.
Fixture location and support
A replacement fixture pad can retain the original mounting holes while changing its working face. We separate the mounting interface from the required support height and contact profile so the new pad locates the part correctly in the existing fixture.
Replacement revision
If a working face, clearance or mounting feature changes during replacement, we keep that change in the drawing revision used for repeat orders. This prevents a later batch from reproducing the dimensions of the superseded part.
POM surface finishing and edge requirements
As-machined acetal surfaces
Identify the faces where normal tool marks are acceptable. Keep a cosmetic requirement separate from the roughness of a bore, seal or sliding face.
Deburred edges and clear passages
Specify edge breaks and passages that must be clear. A sharp locating edge or sealing detail should not be rounded without drawing approval.
A specified finish on the working face
Give the roughness, location and measurement method when it matters to the design. A polished appearance alone does not confirm friction or sealing performance.
Cleaning and identification for your order
Define any cleaning, marking location and protection for shipment. For special finishes or bonding preparation, agree suitability and an acceptance sample before production.
POM Material Records and Inspection
Material Identification
Agree the resin family, manufacturer or stock supplier, grade, color and lot information required. A proposed substitute is a separate decision and should be approved before material is cut.
Dimensional Inspection
Identify the features that need recorded results, the datums and the measurement conditions. Agree sample quantities and the inspection scope before the first delivery, then use the approved revision for repeat orders.
Functional Testing
A dimensional report is not a wear-life, pressure, chemical-resistance or electrical test. Define any additional method, sample quantity, acceptance limits and test responsibility in the order.
What changes the cost of a custom POM part?
Material designation and stock size
The stock supplier, grade, color, blank size and available form affect the material portion of the quote. A large bored sleeve may use a different starting form from a solid block.
Setup changes and difficult features
Deep pockets, narrow slots, multiple orientations and additional gear-cutting operations affect the machining route. A design review can identify changes to discuss without altering a working feature unilaterally.
Inspection, special finishing and records
Recorded dimensions, assembly checks, approved cleaning, individual identification and extra test reports should be included in the same request as machining.
Quantity now and repeat quantities later
Ask for sample, first-batch and expected repeat quantities together. This helps compare setup, tooling and inspection costs on the same basis. Delivery and pricing remain subject to the final quotation.
From an acetal prototype to a repeat order
Review the model and drawing
Confirm the material designation, critical dimensions and intended use. Raise any proposed design or material changes for approval.
Agree a sample and its acceptance
Decide what the sample should demonstrate: dimensions, fit, assembly, appearance or an additional functional test.
Release the approved quantity
Record the drawing revision, material and agreed production route before machining the batch. Agree the inspection scope and delivery arrangement.
Keep the specification consistent on repeat orders
Use the approved revision and material source or agreed alternatives. Review changes to the mating assembly, grade or quantity before another order.
Questions about ordering POM machined parts
How should POM, acetal and Delrin® be specified on a drawing?
POM and acetal name the material family; POM-C and POM-H identify the two main resin types. Delrin® identifies a branded POM-H material. A drawing that requires Delrin® should identify its grade and approved stock source. We retain that specification in the quotation rather than substitute generic POM-C.[1]
Can you machine both natural and black acetal?
Include the color with the exact material specification in your request. Stock availability is checked for the order. Color alone does not identify whether a material is POM-C, POM-H, conductive or suitable for a controlled application.
What tolerances can you hold on a POM part?
Tolerance is reviewed feature by feature against the dimensions, geometry, stock, workholding and inspection condition. Highlight the critical fit and share the mating-part details, and we commit to the accuracy your acetal component and its inspection condition allow.
Do you need the shaft or housing drawing for a bushing?
It helps when the fit is important. Include the shaft, housing, installation method, load and temperature. State whether acceptance is based on the loose part, the installed bore or an assembly test.
Will a POM prototype behave exactly like an injection-molded part?
A machined sample confirms fit and function, while a molded part shrinks and develops different crystallinity, so the molded version still needs its own first-article approval. Agree the purpose of the sample and review the selected resin, stock history, geometry and any process differences before relying on test results.
Can you make gears and rollers from acetal?
Send the full geometry and inspection requirements for review. For gears, include tooth-form data and the mating arrangement. For rollers, include running diameter, bore, hub, load and speed. The production method and any partner involvement are agreed before quotation.
Can I request food-contact or electrical documentation?
List the exact declarations, property limits and test methods you need. These must relate to the proposed grade, color, use conditions and finished part where applicable. A generic POM name is not treated as proof of conformity.
What should I send for a POM machining quotation?
Send a 3D model and matching dimensioned drawing, the exact material or selection requirements, quantity, critical fits, surface finish, inspection scope and requested delivery. Add the mating-part and service details when they affect the design.
Send your POM drawing for a quote
- Matching CAD model and dimensioned drawing
- POM-C, POM-H or the exact approved acetal grade
- Mating component, load, movement and temperature
- Critical fits, finish and agreed inspection condition
- Sample and batch quantities, records and requested delivery
Agree confidentiality and the transfer method before sharing sensitive or restricted files.
PROJECT SUPPORT
Discuss your POM part
Share your drawing, material and quantity. Tell us what you need and we will reply by email.
Material References
Manufacturer references for acetal grades. Use the current documentation for the specified grade. Delrin® is a registered trademark of Delrin USA, LLC.
- Ensinger — POM / acetal overview and Engineering Plastics ManualPOM terminology, material families and grade-dependent properties.
- Delrin — acetal homopolymerBrand terminology and acetal homopolymer background.
- Delrin — parts and shapesMachining stock, clamping, tool condition and part-design considerations.
- Ensinger — wear-modified POM-CAn example of a lubricated acetal formulation. Send the grade you need and we check availability for the order.
