Not properly prepared bar

Tip and Trick – 2011-09-05

TB-DECO (V6)

When loading a new bar into the spindle, the bar feeder usually offers two alternatives with respect to the distance of feed in the chuck :

Bar feeding at cutting level
Bar feeding against the bar stop.

This choice of options is governed by bar preparation and the types of parts being executed ; each of these alternatives has its advantages and disadvantages (see table below).

Bar feeding at cutting level

Advantages	Disadvantages
Prevents execution of an initial, non-compliant part where the bars have not been prepared	Loos of production of one part in the first lathe
	Risk of tool breakage
Risk of tool breakage
Advantages	Disadvantages
No production loss in the first lathe	First part does not comply in the case of non-prepared bars
	Risk of tool breakage

Position the tool at the rear part
face level (cut)

Program a cutting (or facing) movement

Position the tool normally for the operation
provided at station 1

Program normally the operation
provided at station 1

The tip we are proposing today is a third alternative, which avoids tool breakage and the execution of an initial, non-compliant part owing to poor bar preparation. This is achieved by using a tool in position 1, which is capable of carrying out both the operation required and part cropping.

With the TB-DECO, we shall program the facing in the operation boxes before the green flag and normal machining in the boxes that follow (see illustration). With respect to the bar feeder variables, it will be necessary to program the bar feed distance, so as to stop the bar a little further than the cut. This means that when the machine resumes production with a new bar, the tool in position 1 will start by cropping the front of the bar, thereby providing us with a prepared surface to machine the first part in a proper and sure manner.

Important :The operations programmed before the green flag, for purposes of facing the new bar are executed each time AUTO mode starts up, provided a RESET has been executed beforehand.

This tip can only be used provided the following two conditions are met.

MULTIDECO machine with a cross slide in position 1:
MULTIDECO 20/6
MULTIDECO 20/6b
MULTIDECO 32/6i
Tool on support 11, which is capable of executing the necessary operations in the program loop and in the operations preceding the green flag (a special tool can be provided).