Custom machined part
Plastic pistons
- Machined in
- Grooves, lands & ports
- Starting point
- Drawing or worn piston
- Delivered
- Machined, or with seals fitted
- Quantity
- One to production
Custom pistons CNC machined in UHMW, acetal, PTFE, PEEK and other engineered plastics, with seal grooves, lands and ports to your drawing or matched to your worn piston. From one replacement to production runs.
- ±0.002"–±0.005" on critical dimensions
- Family owned in Aurora since 1986
- Expedited service for breakdowns
How it seals
How your piston carries its seal
A piston carries its seal through the bore, so how it seals defines the part. If the seal stays fixed and a smooth rod moves through it, that’s a plunger.
- DIAGRAM: piston with seal sitting in a machined groove, against the bore
Seal in a groove
An O-ring, cup or lip seal sits in a groove machined into the piston.
- What matters
- Groove width, depth and finish, which set how much the seal is squeezed.
- What to send
- The seal part number or size, and the groove if it’s still readable.
- DIAGRAM: plastic piston land sealing directly on the bore
Integral sealing land
No separate seal. The plastic outside diameter itself seals against the bore.
- What matters
- OD size and finish against the bore, and clearance after moisture or heat.
- What to send
- The bore diameter and condition, and the media it runs in.
- DIAGRAM: piston with wear bands either side of the seal
With wear bands
Guide bands keep the piston centered, so the seal isn’t carrying side load.
- What matters
- Band grooves and widths, and how the bands share load with the seal.
- What to send
- The band size or the old bands, with the seal arrangement.
Built some other way? Send an assembly section or photos of the piston in its bore.
What defines the piston
The piston and the bore it runs in
A piston only works with its bore. These are the two halves we need to match.
The piston
- Outside diameter and length
- Seal grooves or sealing lands
- Guide-band grooves
- Ports or cross holes
- Rod or end connection
- Chamfers and lead-ins
The bore it runs in
- Bore diameter and condition
- Bore material and finish
- Stroke
- Alignment
- How it’s assembled
- How it runs
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- Product or fluid
- Grit or contamination
- Load or pressure
- Speed and cycles
- Dry or lubricated
- Temperature
- Cleaning
A worn piston may no longer show its original OD or groove. We measure it, account for the wear and confirm the sizes with you.
Getting a quote
Start with what you have
Any one of these is enough to get a quote started. Pick yours to see what helps.
Send the drawing and we machine to it.
- Quantity
- Plastic, if specified
- Seal part number
Upload drawings, CAD files or photos on the quote form.
Send the old piston, with its seal if you can.
- Bore condition
- The equipment it’s from
- Quantity
Upload drawings, CAD files or photos on the quote form.
Send what you know. We’ll ask for the rest.
- OD and length
- Groove and seal type
- Stroke
Upload drawings, CAD files or photos on the quote form.
Plastics for pistons
Common choices, and why
- UHMW Abrasion- and impact-resistant with low friction, good with gritty product.
- Acetal Stiff and stable, so grooves hold their size. Low moisture uptake.
- PET (Ertalyte) Very stable in wet service, and good for precise sealing lands.
- Filled PTFE Low friction for dry running. Watch for creep at the groove.
- PEEK For heat, steam and harsh chemicals.
- Nylon Tough and wear-resistant. It takes on moisture, which we allow for.
- Detectable grades Metal- and X-ray-detectable plastics, for food lines with inspection.
Where the duty calls for metal, we also machine pistons in aluminum, brass and bronze.
Machined in Aurora
How your pistons are made
±0.002"–
±0.005"
On critical dimensions, depending on the plastic. Specs and CAD files are kept, so a reorder matches the last batch.
-
Grooves cut to your seal
CNC turned to the OD, with seal grooves, lands and guide-band grooves cut to your seal’s dimensions.
CNC turning -
Ports and connections in the same cycle
Cross holes, ports and rod connections machined on live-tooled turning centers.
-
Assembled and ready to fit
We machine the wear bands too, and fit seals, O-rings and retaining rings before shipping, so there’s no second supplier. Assembly service
Evaluating a supplier? See the shop and how we check the work.
Where plastic pistons run
Buyer questions
Plastic piston FAQs
Something else? Call (630) 904-2525.
Often, but it depends on the plastic, load, speed, bore finish and temperature. If your drawing doesn’t specify a plastic, we’ll suggest one suited to dry running.
No plastic is completely immune. Acetal and PET take on very little moisture, while nylon takes on more. Send the exact cleaning, chemicals and temperatures and we’ll suggest suitable plastics.
Food-contact documentation is available for the grades used in food zones. Metal- and X-ray-detectable grades are available, so tell us which your inspection system uses.
We hold ±0.002" to ±0.005" on critical dimensions, depending on the plastic. We review your drawing and confirm the critical dimensions, such as OD and seal grooves, with your quote.
Timing depends on the piston, plastic and quantity, and comes with your quote. For an emergency breakdown, ask about our expedited service.
Not a piston?
Find the right part
We machine almost any plastic part. If yours isn’t listed, describe it in a quote request.
Standard quote
Ready to send your piston details?
Experienced help from your first quote to the finished part.