Mechanical and Fitting

Fitting and Machining N2 - Assignment 1

Occupational Safety

1. Classes of machine guards: - Transmission guards - Point of operation guards

2. Characteristics of a good guard: - It must provide maximum positive protection - It must be corrosion and fire resistant

3. Basic types of guards: - Interlocking guards - Fixed guards - Automatic Guards

4. Safety rules when working with ladders: - Ladders should be equipped with safety feet - Never leave a ladder where it may fall

5. Factors to consider when operating a pneumatic machine: - Check fittings for proper connection - Check the air strainer and clean if necessary - Check the guards provided , be sure that it is properly installed - Check for loose parts and tighten them if necessary - Lubricate machines unless an air line lubricator is used.

Couplings

1. A coupling connects 2 shafts and transmits power from one shaft (motor) to another (driven parts).

2. 2 Types of permanent couplings: - Flange coupling - Marine coupling

3. 2 Types of flexible couplings: - Nylon sleeve coupling - Rubber belt coupling

4. A - Yoke B - Screw C - Cross piece D - Shaft

5. Self aligning Couplings – Universal coupling

Limits & Fits

1. B - Tolerance is the acceptable limits of variation in dimension/size. It is to allow reasonable leeway for imperfections.

C - Allowance is not the same as tolerance; it is the planned difference between dimensions. The difference of size between 2 things e.g. size of hole and size of shaft.

D - Interchange-ability of parts means that it is identical components (parts) that can substitute one another. Manufactured from the same drawing.

2. Bi-lateral tolerance: - Basic size: 0.500 mm - Upper limit: 0.502 mm - Lower limit: 0.498 mm

3. Uni – lateral tolerance: - Basic size: 0.500 mm - Upper