Reaming - Course: Techniques for Machining of Material. Instruction Examples for Practical Vocational Training: Instruction example 6.2.: Indexing bearing

Reaming - Course: Techniques for Machining of Material. Instruction Examples for Practical Vocational Training

		(introduction...)
		Introduction
		Instruction example 6.1.: Bush
		Instruction example 6.2.: Indexing bearing
		Instruction example 6.3.: Flange
		Instruction example 6.4.: Drilling block

Instruction example 6.2.: Indexing bearing

This example serves to practise reaming of blind holes in rotationally symmetrical parts.

Figure

Material

Al 99.5 (Al - aluminium; 99.5% content of pure aluminium; 0.5% impurities)

Dimensions

dia. 60 x 80 mm (pre-machined)

Cutting tools

Centre drill A 3.15; twist drill dia. 26; boring tool for corner work; machine reamer dia. 30 E8, hook tool

Measuring and testing tools

Vernier caliper, depth gauge, dial gauge, inside caliper; limit plug gauge dia. 30 E8

Accessories

Chuck jaws which can be internally turned, taper sleeves, chuck key, coolant and lubricant

Required previous knowledge

Reading of drawings; measuring and testing; centring; drilling; recessing; manual reaming

Explanations to the working drawing

dia. 30 E8:

Ø = diameter, E = disposition in the tolerance zone/standard hole, 8 = quality, 30 nominal size; upper deviation = 30.073 mm. lower deviation = 30.040 mm

The flat shown on the drawing is achieved by a milling operation at a later stage and is not described here.

Sequence of operations		Remarks

1.	Measuring of blank	Undersize blanks are to be separated.

2.	Clamping of workpiece	Type of clamping: “chucking” in chuck jaws which can be internally turned. Check true running. Chuck on dia. 60 mm.

3.	Clamping of tool

4.	Centring	Ensure central position.

5.	Clamping of tool	Use taper sleeves, if necessary.

6.	Drilling of dia. 26	Use coolant. Observe surface pattern. Aluminium is tough material - inclination to cracking, select suitable cutting values (n = approx. 180 r.p.m.). Feed to be guided equally. Length 45 mm!

7.	Clamping of tool	Ensure central position. If necessary, use supporting plates. Short clamping is important. Set bed stop.

8.	Boring dia. 29.7 x 45	Prepare for reaming, produce blind hole. Set block gauge 45 mm. Clean boring of inner face.

9.	Clamping of tool	Pay attention to grind width 5 mm. Clamp in the centre.

10.	Recessing A4 x 0.5	First cut on end face. Produce recess.

11.	Clamping of tool	Mount in tailstock sleeve. Use taper sleeves.

12.	Reaming of dia. 30 E8	n = 30 r.p.m. Reamer to take first cut, pre-inspection by limit plug gauge, inspection of surface pattern. Produce fitting hole, pay attention to 45 mm length. Use spirit as lubricant. Retract reamer with the machine running.

13.	Unloading of workpiece	Clean chucking faces of chuck jaws.

14.	Dimensional and surface finish inspection	Use limit plug gauge. Pay attention to bellmouth, if any. Deburr hole.

Figure