Cnc machining nm09/2


Section 5: Transfer programs to CNC machines



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Section 5: Transfer programs to CNC machines


This section covers methods of transferring programs to CNC machines and loading programs into the CNC machine memory.

Objectives


At the end of this section, you will be able to:

  • list methods of transferring a program into the memory of a CNC machine

  • load a program into a CNC machine memory

  • identify which method of program transfer is suitable for given situations

  • maintain workplace safety standards at all times.

Safety reminders


  • In the workshop, always wear safety glasses, safety boots, hair protection and suitable clothing.

  • Avoid back injuries -lift the correct way.

  • Do not use a machine fitted with a Danger Tag.

  • Know where the first aid station is.

  • Don't run or play in the workshop.

  • Use ear muffs or plugs to protect your hearing.


5.1 Setting up a CNC Milling Machine


Note: Operation of the machine tool is only to be done under the teacher's supervision.

The setting up of the CNC milling machine involves the following procedures:



  • Entering the program in the machine control

  • Checking and editing the program

  • Preparing the work holding devices

  • Mounting tools in the tool changer

  • Setting the tool offsets

  • Selecting and setting a tool change position

  • Establishing the tool and work piece datums

  • Dry running the program.

5.2 Program entering and checking


Programs may be entered into the machine controller by several methods:

  • By direct entry via the machine control keyboard

  • By tape prepared on a punch tape machine from the editor

  • By disc from the editor computer to the on board computer on the machine or a computer set up next to the machine and connected to the machine

  • By direct transfer from the editor computer to the machine controller.

Once the program is entered into the machine control, editing is carried out via the controls keyboard.

The procedures for transfer via disc or direct line vary from one machine to another but the basic principle is to prepare the machine to receive the information and then to prepare the computer to send the information and finally to actually send.

A trap that can be fallen into when transferring information via computer is the fact that the baud rate on both the receiver and the sending machines must be the same.

The correct procedures for transferring data to and from the CNC machine controller will be demonstrated to you by your teacher.


5.3 Safety


Safety should be to Occupational Health & Safety (OH & S) standards before working on CNC machines, in particular attention to:

  • Personal safety

  • Workplace safety

  • Machine safety.

Briefly and generally the following checklist should be covered as a minimum requirement.

  • Personal attire (safety glasses, clothing, shoes etc).

  • Personal attitude (awareness, concentration, distraction, behaviour).

  • Machine condition (operation of guards, contamination level of coolant, security of holding devices and tooling, interlocks operational, hydraulic pressures checked).

  • Machine operation (correct and careful trialing, gripping force at high speed, materials handling/lifting, use of settable barriers, effect of out of balance work).

  • Workplace (oily floors, cluttered work area, lighting ventilation).

Refer to OH & S documents for fully detailed requirements on all aspects of work safety.

Exercise 10 — section 5 — program transfer


Note. This exercise should only be carried out under the supervision of your teacher.

Program transfer


Use available options to transfer the completed program from Exercise 9 into the CNC machine.

Section 6: CNC machine preparation


This section covers the preparation of a CNC machine for operation including work holding, tool installation, pre start checks and machine adjustments.

Objectives


At the end of this section, you will be able to:

  • mount work holding devices

  • install work material

  • install tooling as required

  • set/adjust machine to meet the required specifications

  • maintain work place safety standards at all times

  • explain the concepts of compensating for tool radius

  • identify and carry out workpiece checks before and after machining

  • identify and carry out machine checks before and after machining.

Safety reminders


  • In the workshop, always wear safety glasses, safety boots, hair protection and suitable clothing.

  • Avoid back injuries -lift the correct way.

  • Do not use a machine fitted with a Danger Tag.

  • Know where the first aid station is.

  • Don't run or play in the workshop.

  • Use ear muffs or plugs to protect your hearing.

Special rules for this section


  • take care when handling sharp cutters and tooling

  • do not work on the machine unless your teacher has cleared you to do so

  • ensure all tools will clear other machine parts when mounted in magazine

  • do not make any adjustments to the machine unless your teacher is present.


6.1 Work holding devices

Machine vice


A machine vice can be used in conjunction with parallel strips, although it is preferable to machine soft jaws in order to achieve workpiece support with no loose pieces involved in the set up. For greatest accuracy, soft jaws should be machined in position on the machine.

Fixtures


Similarly, fixtures are most accurate if their locating surfaces are machined in position with the fixture accurately positioned on a riser table or some form of adaptor.

If any fixture can only be located in one certain position on the machine, then the machine position that locates the program origin can be stamped onto the fixture to eliminate setting and checking each time the fixture is used.

Fixtures should at least be aligned accurately in one plane via tee slots.

Simple fixtures designed to hold a part for a once-only run of a single part or a few parts may be simply bolted or clamped.




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