Chapter Questions
Approximately how long ago were thermoplastics developed? (Obj. 31-1)a. 25 yearsb. 50 yearsc. 75 yearsd. 100 years
Another name for plastic is _______. (Obj. 31-1)a. Perchloralethleneb. Polysulfidec. Polymerd. Both b and c
What are the two main types of plastics? (Obj. 31-2)a. Thermoplastics and thermoshere plasticsb. Thermoplastics and thermosetting plasticsc. Thermoplastics and polyvinyl chlorided. Thermoplastics and polyethylene
What form of plastic is transparent? (Obj. 31-2)a. Polyvinyl chlorideb. Polyethylenec. Acrylicsd. Acrylonitrile butadiene styrene
Plastic welding is done on which joints? (Obj. 31-3)a. All the basic joints can be weldedb. Lap and T-jointsc. Butt and corner jointsd. Edge and notch joints
Welding processes for joining plastics are broken down into how many groups? (Obj. 31-3)a. Twob. Threec. Fourd. Five
What two welding processes are very common for repair welding? (Obj. 31-3)a. Hot-plate welding, sonic weldingb. Hot-gas welding, injection weldingc. Resistive implant, induction weldingd. Spin welding, vibration welding
Which is not considered a plastic weld fault? (Obj. 31-4)a. Porous weld and scorchingb. Poor penetration and fusionc. Slag and spatterd. Stress cracking and warping
Plastic welding must have a strength of 100 percent of the base material. (Obj. 31-4)a. Trueb. False
What is an appropriate V-groove angle for an injection weld? (Obj. 31-5)a. $30^{\circ}$b. $60^{\circ}$c. $45^{\circ}$d. $90^{\circ}$
Why are plastics so useful in making products? (Obj. 31-1)
Describe six ways a plastic's type can be identified. (Obj. 31-2)
List the type of plastic represented by each abbreviation. (Obj. 31-2)a. PET _______b. HDPE _______c. PVC _______d. LDPE _______e. PP _______f. PS _______g. ABS _______h. GRP _______
List the key points of why welding is such a popular joining method for plastic. (Obj. 31-3)
What are the three key parameters that must be controlled in making a plastic weld and why? (Obj. 31-3)
Name the two basic types of hot-gas welding torches. (Obj. 31-3)
List the six interrelated factors that offset the strength of a plastic weld. (Obj. 31-4)
Faulty welds are the result of errors. List six of these errors. (Obj. 31-4)
Name the three testing groups used to test plastic welds, and briefly explain each. (Obj. 31-4)
Describe how a crack should be repair welded with a hot-gas welding machine. (Obj. 31-5)