Question & Answer

Why is the term pressworking often used for sheet metal processes?

Extrusion is a fundamental shaping process. Describe it

What are the differences between bulk deformation processes and sheet metal processes?

There are 16 correct answers in the following multiple choice questions (some questions have multiple answers that are correct). To attain a perfect score on the quiz, all correct answers must be given. Each correct answer is worth 1 point. Each omitted answer or wrong answer reduces the score by 1 point, and each additional answer beyond the correct number of answers reduces the score by 1 point. Percentage score on the quiz is based on the total number of correct answers.

17.1 The following equipment is used for crushing and grinding of minerals in the preparation of traditional ceramics raw materials. Which of the pieces listed is used for grinding (two correct answers): (a) ball mill, (b) hammer mill, (c) jaw crusher, (d) roll crusher, and (e) roller mill?

17.2 Which one of the following compounds becomes a plastic and formable material when mixed with suitable proportions of water: (a) aluminum oxide, (b) hydrogen oxide, (c) hydrous aluminum silicate, or (d) silicon dioxide?

17.3 At which one of the following water contents does clay become a suitably plastic material for the traditional ceramics plastic forming processes: (a) 5%, (b) 10%, (c) 20%, or (d) 40%?

17.4 Which of the following processes are not plastic forming methods used in the shaping of traditional ceramics (three correct answers): (a) dry pressing, (b) extrusion, (c) jangling, (d) jiggering, (e) jolleying, (f) slip casting, and (g) spinning?

17.5 The term green piece in ceramics refers to a part that has been shaped but not yet fired: (a) true or (b) false?

17.6 In the final product made of a polycrystalline new ceramic material, strength increases with grain size: (a) true or (b) false?

17.7 Which one of the following processes for the new ceramic materials accomplishes shaping and sintering simultaneously: (a) doctor-blade process, (b) freeze drying, (c) hot pressing, (d) injection molding, or (e) isostatic pressing?

17.8 Which of the following are the purposes of finishing operations used for parts made of the new ceramics (two best answers): (a) apply a surface coating, (b) electroplate the surface, (c) improve surface finish, (d) increase dimensional accuracy, and (e) work harden the surface?

17.9 Which of the following terms describes what a cemented carbide is (one best answer): (a) ceramic, (b) cermet, (c) composite, (d) metal, (e) new ceramic, or (f) traditional ceramic?

17.10 Which of the following geometric features should be avoided if possible in the design of structural components made of new ceramics (three best answers): (a) deep holes, (b) rounded inside corners, (c) rounded outside corners, (d) sharp edges, (e) thick sections, and (f) threads?

What are some design recommendations for ceramic parts?

Liquid phase sintering is used for WC-Co compacts, even though the sintering temperatures are below the melting points of either WC or Co. How is this possible?

Describe the doctor-blade process.

What is the freeze drying process used to make certain new ceramic powders?

Why is raw material preparation more important in the processing of new ceramics than for traditional ceramics?

Why is the drying step, so important in the processing of traditional ceramics, usually not required in processing of new ceramics?

What is glazing in traditional ceramics processing?

What is the name given to the furnace used to fire ceramic ware?

What happens to a ceramic material when it is sintered?

What is the difference between dry pressing and semi-dry pressing of traditional ceramic parts?

What is the process of jiggering?

List and briefly describe some of the plastic forming methods used to shape traditional ceramic products.

Describe the slip casting process in traditional ceramics processing

What is the technical difference between crushing and grinding in the preparation of traditional ceramic raw materials?

List the basic steps in the traditional ceramics processing sequence.

What is the difference between the traditional ceramics and the new ceramics, as far as raw materials are concerned?

For each of the four part drawings in Figure P16.14, indicate which PM class the parts belong to, whether the part must be pressed from one or two directions, and how many levels of press control will be required? Dimensions are mm.

The part shown in Figure P16.13 is to be pressed of iron powders using a compaction pressure of 75,000 lb/in² . Dimensions are inches. Determine (a) the most appropriate pressing direction, (b) the required press tonnage to perform this operation, and (c) the final weight of the part if the porosity is 10%. Assume shrinkage during sintering can be neglected.

2 A bearing of simple geometry is to be pressed out of bronze powders, using a compacting pressure of 207 MPa. The outside diameter = 44 mm, the inside diameter = 22 mm, and the length of the bearing = 25 mm. What is the required press tonnage to perform this operation?

In a certain pressing operation, the metallic powder fed into the open die has a packing factor of 0.5. The pressing operation reduces the powders to 2/3 of their starting volume. In the subsequent sintering operation, shrinkage amounts to 10% on a volume basis. Given that these are the only factors that affect the structure of the finished part, determine its final porosity.

Given a large volume of metallic powders, all of which are perfectly spherical and having the same exact diameter, what is the maximum possible packing factor that the powders can take?