Reaming - Course: Techniques for Machining of Material. Instruction Examples for Practical Vocational Training: Instruction example 6.1.: Bush

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

This example serves to practise reaming of through holes in rotationally symmetrical parts held in a chuck.

Figure

Material

9 S 20 K (9 = 0.09% carbon, S 20 = 0.2% sulphur content, K = cold drawn)

Dimensions

dia. 36 x 60 mm

Cutting and operating tools

Centre drill A 2.5, twist drill dia. 15, three-lipped twist drill dia. 15.75, machine reamer dia. 16 H7

Measuring and testing tools

Vernier caliper, limit plug gauge dia. 16 H7, dial gauge.

Accessories

Taper sleeves, drill chuck, soft chuck jaws, coolant and lubricant

Required previous knowledge

Reading of drawings, measuring and testing, manual reaming, centring and drilling

Explanations to the working drawing

	= admissible true-running error 0,1 mm to A
A	= reference plane
dia. 16 H7	= diameter

16	-	nominal size: upper deviation 16,018 mm, lower deviation 16.00 mm
H	-	disposition in the tolerance zone/standard hole
7	-	quality

Sequence of operations		Remarks

1.	Measuring of blank	Undersize blanks with respect to outside diameter or length are to be separated.

2.	Clamping of workpiece	Type of clamping: “chucking” in chuck jaws which can be internally turned. Check true running, turn jaws internally, if necessary. Chuck on dia. 36 mm

3.	Clamping of tool	Mount drill chuck in tail-stock sleeve, use taper sleeves, if necessary.

4.	Setting of cutting values	(calculation)

5.	Centring	Ensure central position. Align tailstock, if necessary.

6.	Clamping of tool	Mount taper shank of twist drill in tailstock sleeve. Use taper sleeves, if necessary.

7.	Drilling of dia. 15	Use coolant.

8.	Clamping of tool	Mount in tailstock sleeve use taper sleeves, use coolant.

9.	Boring	Use coolant.

10.	Clamping of tool	Mount in tailstock sleeve.

11.	Reaming dia. 16 H7	n = 60 r.p.m. Reamer to take first cut, pre-inspection by limit plug gauge, inspect surface finish, ream equally, use coolant/lubricant, return reamer while machine is running.

12.	Switch off machine

13.	Unloading	Clean faces of chuck jaws.

14.	Dimensional and surface finish inspection	Use limit plug gauge, consider bellmouth, if any. Deburr the hole at both ends by suitable means (counter-bore, turning tool, three-square scraper).

Figure