Material guide Extruded acrylic
Extruded acrylic is enough when the edge is not the product and the joint does not have to disappear. It is the normal sheet for a thin back, a divider, a simple bend, and a slotted part that needs consistent thickness. It is the wrong default for a polished show face. Specify it on purpose. Do not let a quote switch to it in silence.
The short answer
Decision rule. If no polished edge faces the customer and no solvent joint has to vanish, extruded acrylic is usually enough — and it is the sheet you should name, so you are not billed for cast. If either of those is true, start with cast on that member.
What extruded sheet is
Extruded acrylic is PMMA melted and pushed through a die. ISO 7823-2 covers that sheet. It is generally the lower-cost route and often the more consistent thickness. It is still acrylic. A trade name on the email does not say which process made the blank.
What buyers notice is the edge and the joint, not the chemistry. A laser-cut extruded edge is typically frosted. Heat bending is common and sensitive to temperature. Solvent bonding is possible and less forgiving than cast-to-cast. None of that makes the sheet unsuitable. It makes it suitable for a stated list of parts.
Where it is enough
Hidden back or base
Not polished, not a show joint. Extruded is the usual cost member. Write “extruded, hidden” so the saving is agreed.
Internal divider
A divider that does not present an edge to the camera. Consistent thickness helps the slot. Extruded fits this job.
Simple bent holder
One lip, no diamond edge. Brochure holders and light stands are the classic extruded part. Say so on the RFQ.
Slotted, press-fit assembly
Extruded’s more uniform gauge is the reason to choose it, provided the slotted edge is not also a polished show edge.
Short-run graphic panels and internal fixtures sit in the same group: the face is clear enough, the edge is not the brand, and replacing the part is acceptable.
Where it is not
- A cosmetic cube whose edges are polished and whose joints should disappear. That is cast.
- A thick optical block or plinth with a finished edge. Extruded is not the usual route once the part is thick and the edge is the look.
- A silent swap. If the sample was cast and the quote does not say extruded, do not assume the lower number kept the same sheet.
Outdoor life is not on this list. Weathering is a grade question on either route. Extruded is not “indoor only,” and cast is not a UV specification.
Cast on the show face, extruded behind
A box can use both. Cast on every face and every joint the customer sees. Extruded on the back, the base, or a divider. That mix is a normal cost decision. It is also a specification: if you do not write it, one factory will price all-cast and another will price all-extruded, and the two numbers will not be the same product.
| Member | Usual route | Why |
|---|---|---|
| Show wall, lid face | Cast | Polished edge, clear joint |
| Hidden back | Extruded | No show edge; cost |
| Internal divider | Extruded | Fit and cost, if the edge is hidden |
| Bent lip on a holder | Extruded | One bend, no polish |
| Thick plinth | Cast | Thickness and a finished edge |
Those parts, in acrylic, are the usual retail set: boxes, trays, and display stands.
What to write on the RFQ
- PMMA, extruded — and on which members.
- Whether any edge is polished. If yes, expect a different result from cast, or move that member to cast.
- Nominal thickness, and whether a slot or a fit depends on it.
- That extruded is intentional, so a lower price is not read as a downgrade.
Sanait will treat “acrylic” as incomplete until the route is stated. Intake is on the FAQ. Scope is on the about page.
FAQ
Is extruded acrylic good enough for a display?
For a hidden member, a simple bend, or a divider, yes. For a polished show face with clear joints, no — that member should be cast.
Why do factories like extruded for some parts?
Lower sheet cost and more consistent thickness. Both are useful when the edge is not the product.
Will an extruded edge polish like cast?
Not to the same result. A frosted laser edge can be polished, and it will still read differently from a cast polished edge. If the edge is the look, specify cast.
Is extruded weaker?
It is a different route, not a ranked strength. Do not publish an impact or clarity number without the grade and the method. Choose it for fit and cost, not as a “weaker acrylic.”
Can I solvent-bond it?
Yes, with more care. For a joint that should disappear on a show box, use cast on both sides of that joint.
How do I stop a silent downgrade?
Write extruded where you want it, and cast where you need it. A quote that does not restate the route is not ready to compare.
Sources
The extruded route is defined by the sheet standard. Tolerances belong to that standard and the mill, not to a buying-guide percentage.
- ISO 7823-2:2003, Plastics — Poly(methyl methacrylate) sheets — Part 2: Extruded sheets. iso.org
- ISO 7823-1:2003, Plastics — Poly(methyl methacrylate) sheets — Part 1: Cast sheets. iso.org
- “Poly(methyl methacrylate).” Wikipedia. en.wikipedia.org
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