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Plastic FAQ'S

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Can Dotmar cut material to size?


Yes, all Dotmar branches equipped with saws and will be able to cut most materials to size.
Contact your nearest Dotmar branch to discuss your requirements.

Can Dotmar produce finished parts?


Yes, Dotmar can produce a wide variety of finished parts in our machining facilities.
Conversion of semi-finished t stock shapes into finished plastic parts is performed by thermoplastic  trained, technical teams using state of the art machining facilities. Dotmar has 4 Technical Centres in Australia equipped with state-of-the-art equipment - CAD/CAM Manufacturing & Design, CNC “ Machining Milling / Routing / Spindle Moulding.

What are machining tolerances?


Tolerance is the range of dimensions within the finished part is produced (for example- diameter 100mm + or 0.2mm). These are important as they govern how parts will fit when assembled.
For most work performed Dotmar machines to + or 0.2mm.

What does long and short term operating temperature mean?


The operating temperature of thermoplastics is the minimum and maximum temperatures at which a material or manufactured parts can operate in application without an affect to its properties. Operating temperature guidelines can be indicated as long or short term.
Long term operating temperature is typically measured at 20 000 hours and is an indication of total part life.
Short term operating temperature is where the material or manufactured part is periodically exposed to extreme temperatures for relatively short intervals and then returned to the normal operating temperature range.

What is the difference between cast and extruded grades of nylon?


Cast and extruded nylons are produced using different manufacturing methods which in turn affect the properties of the material.
Extruded grades are generally produced in smaller thickness and diameter. Mechanical dampening of extruded grades is superior.
Cast grades exhibit higher mechanical strength, stiffness, heat, impact strength, creep resistance and wear resistance.

What is stress cracking or crazing?


Environmental stress cracking is a major cause of failure in plastics. It is caused by a combination of exposure to aggressive chemicals and tensile stress. Stress cracking is evidenced by numerous small cracks on the material surface. This can result in catastrophic failure of the material.

Can Engineering Plastics by used outdoors?


Dotmar has a range of materials that are resistant to both UV exposure and moisture.
Some grades of Engineering Plastics that have not been UV stabilized will degrade in time when exposed to UV.

Can Dotmar help in selecting the correct Engineering Plastic material?


Yes - Dotmar employs technical skilled staff and has an ongoing in-house training programme to ensure staff is trained on our large range of engineering plastic products.
In addition, we also offer a technical support incorporating specialized software for bearing, sheave and vessel calculations.

Can plastics replace metals and other conventional materials?


Yes - In most cases engineering plastics provide a durable, lightweight and cost effective solution.

How does polycarbonate compare to acrylic?


Polycarbonate is highly impact resistant, whereas acrylic is not. This makes it much more suitable for safety and glass replacement applications.



How can Engineering Plastics be bonded?


Many of Dotmar's thermoplastic materials can be fixed with adhesives (Please check with your local branch for further info). Engineering plastics can also be fixed with mechanical fixings. (screws or rivets)
Some products, like for example PE are not ideally suited for adhesive bonding and can be welded.

Does Dotmar have materials suitable for food contact?


Yes - Dotmar carries a wide range of such materials and is able to provide a solution for many food contact applications.

Are Dotmar™ Engineering Plastic materials recyclable?


Yes, most thermoplastics are recyclable and can be re-ground and used to manufacture numerous other plastic items.

Can Polycarbonate sheet be used outdoors?


Not all grades of polycarbonate are UV stable and suitable for outdoor use and will generally degrade and turn yellow after prolonged exposure to UV. However, manufacturers of polycarbonate sheet will either use UV stabilized resins or co-extrude a UV stable layer on the sheet during the manufacturing process. This changes the properties and therefore, the scope of applications.
Dotmar's Polycarbonate UVX is manufactured with UV protective coatings on both sides that offer excellent weathering properties, whilst maintaining high clarity and impact resistance.

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