Reaming - Course: Techniques for Machining of Material. Instruction Examples for Practical Vocational Training: Instruction example 6.3.: Flange

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 6.3.: Flange

This example serves to practise reaming of stepped holes in rotationally symmetrical parts. It is to be assumed that the outer contours of the parts have been produced already.

Figure

Material

GGL 25 (GG = cast iron, L = flakes, 25 = 250 MPa tensile strength)

Dimensions

dia. 60 mm, 40 x 65 mm (pre- machined)

Cutting tools

Centre drill A 2.5; twist drill dia. 18, boring tool for corner work; machine reamer dia. 20 H7; machine reamer dia. 40 F8; hook tool

Measuring and testing tools

Vernier calipers limit plug gauge dia. 20 H8, dia. 40 F8; dial gauge, depth gauge, inside caliper.

Accessories

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

Required previous knowledge

Reading of drawings; measuring and testing; centring; drilling; counterboring/countersinking; recessing, manual reaming

Explanations to the working drawing

dia. 20 H7:	upper deviation	=	20.021	mm
	lower deviation	=	20.000	mm
dia. 40 F8:	upper deviation	=	40.064	mm
	lower deviation	=	40.025	mm

Sequence of operations		Remarks

1.	Measuring of blank	Undersize blanks (diameter and/or length) to be separated.

2.	Clamping of workpiece	Type of clamping: “chucking” in stepped chuck jaws which can be internally turned. Chuck on dia. 40 in direction of work-spindle. Check for true running. If necessary, turn jaws internally.

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

4.	Centring	Ensure central position.

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

6.	Drilling	No coolant is required for cast iron. Produce through hole.

7.	Clamping of tool	Ensure central position. Use supporting plates and for round cross section Vee-supports. Chuck as short as possible. Consider machining length to be 65 mm. Set bed stop. Attention! Short-chip material - use safety goggles.

8.	Boring of dia. 19.8	Prepare for reaming, produce through hole.

9.	Boring of dia. 39.5 x 30	Use 30 mm block gauge. Clean turning of face. Produce blind hole, prepare for reaming.

10.	Clamping of tool	Pay attention to 5 mm grind width. Ensure central position.

11.	Recessing A5 x 0.5	Take first cut on end face, produce recess.

12.	Clamping of tool	Use floating holder, mount tool with holder in tailstock sleeve.

13.	Reaming of dia. 20 H7	Take first cut, dimensional and visual inspection. Ream through, retract reamer.

14.	Clamping of tool	Use floating holder.

15.	Reaming of dia. 40 F8	Take first cut. Dimensional and visual inspection. Finish-ream paying attention to transition faces between dia. 20 H7 and dia. 40 F8.

16.	Unloading

17.	Dimensional and surface inspection	Test with limit plug gauge.

Figure