Frequently Asked Questions
Please see below for our most frequently and commonly asked questions. Should you have any other questions or queries regarding our products or services, please do not hesitate to contact us.
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What is the difference between Acrylic, Plexiglas and Perspex, and why use it?
The main differences between Acrylic, Plexiglas and Perspex
PolyMethyl MethAcrylate (PMMA) has the common name Acrylic. Plexiglas, Perspex and Polycast are brand names for Acrylic from suppliers such as Rhom and Lucite.
Acrylic has excellent optical properties with light transmission typically around 92% and a refractive index of 1.49. It has good abrasion resistance, is easier to process versus glass and approximately half of it’s weight. It has good chemical resistance to many common chemicals and good flexural strength. It is also relatively widely available and cost effective versus many other engineering plastics.
What causes cracking & crazing in Acrylic & plastics
The majority of times you see cracking and crazing in plastics such as Acrylic, Perspex, Plexiglas (PMMA), Polycarbonate (PC) and Ultem (PEI) is due to lack of the correct heat treatment. These such plastics need careful normalising and annealing steps throughout the machining, bonding and polishing process.
Should I specify Cast or Extruded Acrylic / Plexiglas / Perspex PMMA?
Cast Acrylic has far less stress in the material than extruded Acrylic due to the nature of manufacture, so should be used whenever possible as it is of far higher quality. Extruded Acrylic is also dimensionally less stable, can stretch or burn more easily, is softer and is far more prone to cracking even with heat treatment. You can source rods or tubes of Acrylic as a base material in a cast form, but these still go egg shaped with heat treatments, so Carville normally produce our own rods and tubes from sheets of cast Acrylic after in-house heat treatment by turning as we can then guarantee dimensional stability.
Are the parts Carville supply suitable for medical devices or IVD applications?
Carville have been producing precision machined plastic parts and bonded manifolds for medical devices for almost forty years. These are often critical to function components in class III medical devices so must adhere to the strictest standards in terms of processes, materials and procedures. We support our client’s ISO14385 requirements with full documentation and full traceability on the entire process from certified in bound material to final despatched parts including full dimensional reports when required. We are also subject to unannounced audits by notified bodies including the FDA to support our clients.
Do Carville support consignment and schedule delivery agreements?
Carville work in many fast paced and demanding industries and therefore understand the needs to a secure and reliable supply chain as well as guarantee lead times and stock availability. Carville have supply framework agreements with a range of customers in Europe, Asia and the USA. These are always tailored to the individual client’s needs including features such as stock holding at Carville, consignment stock on client’s site, kan ban systems, bespoke packaging guaranteed call-off windows.
Do you produce prototype quantities and high volumes?
Carville work’s with clients from early concept prototypes, through to high volume series production. A key advantage of Carville’s approach to precision machined plastic parts and bonded manifolds, is the same fundamental process is used for the early, low volume prototypes as with the series production, so any test results from early development work can be directly translated to production volume performance. We can produce one-off parts up to volumes of 2,000 pcs per day depending on the complexity.