Carville Ltd - About Carville

The most cost effective way to produce materials such as Acrylic is to use either a casting or extrusion process. Although cost effective, cast acrylic or extruded acrylic materials can be highly stressed and may distort during the manufacturing processes.

To ensure stable dimensions and a long life for precision machined component parts, it is essential that materials are correctly heat treated to remove internal stress. Carville will not manufacture plastic component parts without fully heat treating the base material at the pre-production stage.

On materials such as acrylic (PMMA), these initial heat treatment processes can result in material shrinkage of between 2% and 4%.

All plastic materials used by Carville are normalised using controlled heat treatment processes before any machining operations take place.

During the production process, all components are stage annealed to remove any stresses that may have been induced due to the machining processes.
 

Carville use four principal methods of bonding Acrylic and other plastics:

Diffusion Bonding
The diffusion bonding process allows plastic materials to be joined without the use of solvents or adhesives. The material is joined at a molecular level which ensures that any thermal expansion or contraction of the material will not have a detrimental effect.

HAB Bonding
As the fluidic application demands within the medical sector have increased, chemistries have become more aggressive and sample sizes have reduced. These changes have resulted in a demand for smaller micro fluidic style devices that can be produced in alternative engineering grade materials.

Carville have worked with clinical diagnostic companies on the development of this new HAB manufacturing technique and supply finished component parts to customers in UK, Europe, Asia and the USA.

Plastic Cementing
Polymerising cements can be used to produce strong, optically clear joints that are cosmetically attractive. It is important that plastics joined with polymerising cements are suitably heat treated to remove internal material stress. Failure to heat treat may result in solvent induced stress crazing or cracking of the material.

Solvent Cementing
This is a low cost method with a limited number of applications. Plastic materials may be joined by applying a suitable solvent and then clamping the materials together. It is imperative that the materials to be joined are correctly heat-treated. Failure to heat treat may result in solvent induced stress crazing or cracking of the material.
 

Carville have manufacturing procedures that ensure good material handling and a high level of machined finish. We aim to achieve the best possible machine finish to minimize the requirement for post machine plastic polishing.

When polishing is necessary, there are a number of ways to polish plastic materials to achieve the end customer’s required surface finish. These techniques will vary depending upon the final application.

Plastic polishing techniques for lenses are different from those applied to produce a luxurious finish to a high end writing instrument. Carville has developed a number of plastic polishing techniques to achieve the required internal and external finishes for each application.

Customers often ask Carville about flame polishing. This is not a technique used by Carville. Polishing a precision machined plastic component using a flame will result in uneven heat distribution and material stress. Introducing stress to the material may result in future component failure. Flame polishing is not used or recommended by Carville.
 

Carville has extensive experience in acrylic and plastic fabrication. We produce large complex engineering components by thermoforming plastic sheet materials and fabricating them using suitable cements and bonding techniques.

Carville has a successful track record in supporting new and established businesses with design, development and project management work. Carville aims to offer our customers advice on part design to achieve the most reliable and economic manufacturing costs.

Working with a diverse customer base, Carville recognise that customers may require low volume prototype parts to achieve proof of concept before they can progress to larger production quantities. Carville understand the need for short lead-time plastic prototypes and work to support our customers when possible.

With a wide range of CNC machines and skilled personnel, the Carville facility is equipped to produce single unit plastic prototypes to meet customer’s short lead-time requirements.

Carville can support customers with project management services to take a customers concept to prototype manufacture and then on to full production.