Setting CNC milling machines for production
Overview
This standard identifies the competences you need to prepare and set up Computer Numerical Control (CNC) three axis or five axis milling machines or CNC machining centres, in accordance with approved procedures. This involves selecting the appropriate workholding devices, and mounting and positioning them to the machine table in the designated or appropriate position, as required by the machine-operating program. You will also be required to select the appropriate milling cutters to use, and to mount and secure them to the appropriate tool holding devices. You will be expected to place the tools in the relevant positions within the tool change magazine or carousel, where this is applicable.
You will need to ensure that all the tools have been allocated a relevant tool number and that the relevant data on their co-ordinates and datum positions are entered into the operating program and machine. This will involve loading and proving the component program, checking for errors/faults, editing and saving program changes. You must produce trial components and prove the machine is working satisfactorily before declaring the machine ready for production. Making adjustments to settings to achieve specification, and solving machine-related problems during production, will also form part of your role.
Your responsibilities will require you to comply with organisational policy and procedures for the machine setting activities undertaken, and to report any problems with the equipment, tooling, programs or setting-up activities that you cannot personally resolve, or are outside your permitted authority, to the relevant people. You will be expected to work with a minimum of supervision, taking personal responsibility for your own actions and for the quality and accuracy of the work that you carry out.
Your underpinning knowledge will provide a good understanding of your work, and will provide an informed approach to the setting-up procedures used. You will understand the CNC milling machine used, and its application, and will know about the workholding devices, tooling, materials, machine operating program and setting-up procedures, in adequate depth to provide a sound basis for setting-up the equipment, correcting faults and ensuring the work output is produced to the required specification.
You will understand the safety precautions required when working with the machine and its associated tools and equipment. You will be required to demonstrate safe working practices throughout, and will understand the responsibility you owe to yourself and others in the workplace.
Performance criteria
You must be able to:
- work safely at all times, complying with health and safety and other relevant regulations, directives and guidelines
- follow the correct specifications for the component to be produced
- determine what has to be done and how the machine will be set to achieve this
- mount and set the required work-holding devices, work piece and cutting tools
- set the machine tool operating parameters to achieve the component specification
- check that all safety mechanisms are in place and that the equipment is set correctly for the required operations
- complete the required production documentation
- deal promptly and effectively with problems within your control and report those that cannot be solved
Knowledge and Understanding
You need to know and understand:
- how to work safely at all times, complying with health and safety and other relevant regulations, directives and guidelines
- how to start and stop the machine in normal and emergency situations
- the importance of ensuring that the machine is isolated from the power supply before mounting cutters and workholding devices
- the hazards associated with working on CNC milling machines and how to minimise them and reduce any risk
- the importance of wearing the appropriate protective clothing (PPE) and equipment, and of keeping the work area clean and tidy
- how to handle and store milling cutters safely and correctly
- how to save the programs in the appropriate format, and the importance of storing programs and storage devices safely and correctly, away from contaminants and possible corruption
- the methods and procedures used to minimise the chances of infecting a computer with a virus
- the implications if the computer you are using does become infected with a virus and who to contact if it does occur
- how to extract and use information from engineering drawings or data and related specifications (to include symbols and conventions to appropriate standards) in relation to work undertaken
- how to interpret first and third angle drawings, imperial and metric systems of measurement, workpiece reference points and system of tolerancing
- how to read and interpret CNC drawings and extract the relevant information
- the range of workholding methods and devices that are used on CNC milling machines
- why it is important to set the workholding device in relation to the machine axis and reference points
- the methods of setting the workholding devices, and the tools and equipment that can be used
- the range of cutting tools that are used on CNC milling machines, and typical applications
- the use of tungsten carbide, ceramic and diamond indexible tips, and the factors which will determine their selection and use
- how to check that the cutting tools are in a safe and serviceable condition
- the various tool holding devices that are used, and the methods of mounting and securing the cutting tools to the tool holders
- the advantages of using pre-set tooling, and how to set the tooling using setting jigs
- the use of tool magazines and carousels, and how to position and identify the tools in relation to the operating program
- how to place the machine into the correct operating mode, and how to access the program edit facility in order to enter tooling data (such as tool lengths, tool offsets, radius compensation)
- how to conduct trial runs using single block run, dry run, and feed and speed override controls
- why you would conduct a full dry run and single block run
- the items that you need to check before allowing the machine to operate in full program run mode
- how the various types of materials used will affect the feeds and speeds that can be used
- the application of cutting fluids with regard to a range of different materials, and why some materials do not require the use of cutting fluids
- typical problems that can occur with the setting up of the tooling and workholding devices, and what to do if they occur
- the extent of your own responsibility and to whom you should report if you have problems that you cannot resolve
Scope/range
Scope Performance
- Carry out all of the following during the setting-up activities:
- obtain and use the appropriate documentation
- adhere to procedures or systems in place for risk assessment, personal protective equipment and other relevant safety regulations and procedures to realise a safe system of work
- follow safe practice/approved setting up procedures at all times
- confirm that the correct operating program has been loaded
- check that the tooling is in a usable condition
- ensure that the workpiece is correctly positioned and secured without distortion
- update the program tool data, as applicable
- ensure that correctly adjusted machine guards are in place
- leave the work area and machine in a safe and appropriate condition on completion of the activities
- Prepare one of the following CNC milling machines in readiness for production:
- CNC three axis milling machine
- CNC five axis milling machine
- CNC machining centre
- Position and secure workpieces using two of the following workholding methods and devices:
- machine vices
- pneumatic or magnetic table
- ancillary indexing devices
- fixtures
- direct clamping to machine table
- angle plate
- chucks
- other specific workholding device
- Select and mount six of the following types of milling cutters to the appropriate tool holding device:
- face mills
- twist/core drills
- reamers
- special profile cutters
- side and face cutter
- end mills
- boring tools
- slot drills
- other specific cutters
- Prepare tooling for operation by carrying out all the following activities, as applicable to the machine type:
- positioning tools in the correct position in the tool magazine or carousel
- checking tools have specific tool number in relation to the operating program
- entering all relevant tool data to the operating program (tool lengths, tool offsets, radius compensation)
- presetting tooling using setting jigs/fixtures
- setting tool datum
- saving changes to programme (as appropriate)
- Set up the machine to produce components, combining different operations, covering eight from:
- flat faces
- holes on pitch circles
- external profiles
- steps/shoulders
- parallel faces
- holes linearly pitched
- enclosed slots/recesses
- angular faces
- circular/curved profiles
- internal profiles
- open ended slots
- special forms (such as concave, convex)
- faces that are square to each other
- Machine components made from one of the following types of material:
- ferrous
- stainless
- non-ferrous
- non-metallic
- Set the machine to produce components within all of the following quality and accuracy standards, as applicable to the operations performed:
- components to be free from false tool cuts, burrs and sharp edges
- surface finish 32µin or 0.8µm
- reamed and bored holes within H8
- flatness and squareness 0.001" per inch or 0.025mm per 25mm
- angles/tapers within +/- 0.25 degree