Available online
Description
The programme adopts the problem of selecting a suitable material from which to manufacture a gear wheel, and refers to techniques and principles already taught.
The programme adopts the problem of selecting a suitable material from which to manufacture a gear wheel, and refers to techniques and principles already taught.
| Module code and title: | TS251, An introduction to materials |
|---|---|
| Item code: | TS251; 07 |
| First transmission date: | 28-04-1973 |
| Published: | 1973 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:24:25 |
| + Show more... | |
| Producer: | Colin Robinson |
| Contributors: | Peter Chapman; Ken Reynolds |
| Publisher: | BBC Open University |
| Keyword(s): | Film clips; Gear wheel; Graphics; Manufacturing; Materials |
| Footage description: | Peter Chapman introduces the programme which will review the concepts covered in the first 6 units. It takes the form of a discussion on the suitability of metals against polymers as engineering materials. Ian Boustead gives the polymer side in a discussion on the question "What materials could a gear wheel be made from?". Boustead uses animated graphs to aid his discussion. The graphs show the thermal properties of plastics which limit their use as engineering materials under certain circumstances (The glass transition). Shot of a table showing glass transition and Young's modulus values of several polymers. Boustead uses this information as a basis for his choice of suitable polymers for gear wheel manufacture. Ken Reynolds presents the case for metals. He does so in the context of the same question (What materials could a gear wheel be made from?) Micrograph of a cast iron specimen which contains a small percentage of graphite. Reynolds explains how the addition of graphite to cast iron improves the Iron's machinability. Reynolds discusses brass as a possible candidate for gear wheel manufacture. Micrographs of 2 brass alloys. Reynolds discusses their properties and suitability. Ian Boustead discusses methods which could be used to manufacture polymer gear wheels. He begins with the Injection moulding process. Animated diagrams show the injection moulding of a dustbin. Opitical micrograph of a polymer with a random spherulite arrangement. Optical micrograph of a polymer with spherulites oriented to the direction of flow. X-ray diffraction patterns for both of the above. Boustead discusses the effect of spherulite orientation on the engineering properties of polymers. Boustead discusses the possibility of machining plastics to a desired shape. Problem of glass transition temperature again arises. Ken Reynolds discusses methods which could be used to manufacture a metal gear. He shows several types of gear wheels and explains how they were manufactured. Punching, extrusion, forging, and machining processes are each explained in turn and an example of the product shown. Reynolds explains a method of improving the machining qualities of a metal by the addition of small percentages of another substance such as graphite. He gives as an example brass, plus 1% graphite. Micrograph of the brass shows that the addition of the graphite has improved the machining properties. Ian Boustead discusses the suitability of polymer materials for use at high termperatures. He covers both the thermosetting and thermoplastic polymers. Ken Reynolds discusses high temperature limitations on metals for engineering materials. He uses an animated graph to show the relationship between the strength of the metal and its temperature. Effect of lubricants such as oil and grease on polymers examined by Boustead. Effect of water, particularly sea water, on metal engineering materials taken up by Reynolds. He discusses ways in which the problem can be overcome. Chapman, Boustead and Reynolds examine a food mixer made of steel and plastic. They discuss the possible reasons for the use of these materials. Credits. |
| Master spool number: | 6HT/70909 |
| Production number: | 00525_1025 |
| Videofinder number: | 1559 |
| Available to public: | no |
