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Chapter 20. Processes Used to Separate Plastic Materials. Objectives. Die cutting Extrusion cutting Hot wire cutting. Introduction. Plastic sheets, rods, and tubes are usually cut using fine-tooth blades with approximately 12 teeth per inch.
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Chapter 20 Processes Used to Separate Plastic Materials
Objectives • Die cutting • Extrusion cutting • Hot wire cutting
Introduction • Plastic sheets, rods, and tubes are usually cut using fine-tooth blades with approximately 12 teeth per inch. • Most plastics can be cut with traditional metal removing processes such as blanking, shearing, or die cutting. • The International Association of Plastics Distributors (IAPD) provides an online database to help select the best cutting parameters for specific materials and tools.
Machining Plastics • Coolants are normally not required for machining operations other than drilling and parting. • In most cases a fine tooth blade is used to cut plastics. • Plastics have a machining speed of approximately 220 fpm (feet per minute) compared to soft cast iron of 125 fpm.
Die Cutting • Die cutting is used to cut parts such as gaskets and labels from various materials including plastics, rubber, foam, paper, and composites. • Precise control allows it to be used for self adhesive materials without penetrating the paper or film backing (fig 20-8, page 303). • Hot wire cutting is used for cutting plastic foam.
Grinding • Grinding is used to recycle plastics. • Four types of grinders used are: light duty grinder, auger fed grinder, medium duty grinder, and heavy duty grinder. • Small grinders with motors up to 40 hp are capable of handling scrap with a wall thickness of approximately ¼ inch. • Auger fed grinders are used when the manufacturing process is automated or semi automated. • Medium duty grinders with motors up to 100 hp are capable of grinding stock up to ½ inch thick. • Heavy duty grinders with motors up to 400 hp are used for large parts .
Summary • The International Association of Plastics Distributors (IAPD) provides an online database to help select the best cutting parameters for specific materials and tools. • Plastics have a machining speed of approximately 220 fpm (feet per minute). • Die cutting is used to cut parts such as gaskets and labels from various materials including plastics, rubber, foam, paper, and composites. • Grinding is used to recycle plastics.
Home Work • 1. What does the International Association of Plastics Distributors (IAPD) provide? • 2. What is the machining speed of plastics? • 3. Where is die cutting used? • 4. What is one application for grinding of plastics?