Setting CNC optical grinding and polishing machines for production
Overview
This standard identifies the competences you need to prepare and set up optical grinding and polishing computer numerical controlled (CNC) machines, or CNC machining centres, in accordance with approved procedures. You will be expected to select the appropriate workholding devices, and to mount and secure them to the machine. You will also be required to select the appropriate grinding and polishing wheels and equipment, to mount and secure them to the appropriate holder, and to place the grinding/polishing wheels in the relevant positions within the slides or tool change magazine/carousel.
You will need to ensure that all the grinding/polishing wheels 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. You will also be required to produce tool path information for each set-up, and to edit where required. This will involve loading and proving component programs, checking for errors/faults, and editing and saving program changes.
You must produce trial components and prove that 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 that 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 optical grinding and polishing machine used, and its application, and will know about the workholding devices, grinding and polishing wheels, machine operating programs and setting-up procedures, in adequate depth to provide a sound basis for setting up the equipment, correcting faults and ensuring that the work output is to the required specification.
You will understand the safety precautions required when working with the machine and with 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, set and secure the required workholding devices, workpiece 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
- produce trial/first-off components to prove the machine settings
- 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 hazards associated with working on CNC optical grinding and polishing machines and how to minimise them and reduce any risks
- the Abrasive Wheel Regulations covering the use and operation of grinding wheels and equipment
- the importance of ensuring that the machine is in safe mode before mounting grinding wheels and workholding devices
- 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 optical grinding and polishing wheels, and programs 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
- the range of workholding methods and devices that are used on CNC optical grinding and polishing machines
- why it is important to set the workholding device in relationship to the machine datums and reference points
- the methods of setting the workholding devices, and the tools and equipment that can be used
- the range of grinding and polishing wheels that are used on CNC optical grinding and polishing machines, and their typical applications
- how to check that the grinding wheels are in a safe and serviceable condition
- plated bonded, ceramic and diamond bonded wheels, and the factors which determine their selection and use
- the various grinding tool holding devices that are used, and the methods of correctly mounting and securing the grinding wheels to the machine spindle and tool holders
- the advantages of using pre-set tooling, and how to set the tooling using jigs/fixtures
- the use of magazines and carousels, and how to position and identify the grinding wheels in relationship 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
- how to conduct trial runs, using single block run, dry run and feed/speed override controls
- why you would conduct a full dry run and single block run
- the settings that you need to check before allowing the machine to operate in full program run mode
- how the various types of material used will affect the feeds and speeds that can be used
- the application of cutting fluids in relationship to a range of materials being machined
- 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:
- 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
- confirm that the correct operating program has been loaded
- obtain the correct grinding and polishing wheels, and check that they are in a safe and usable condition and are appropriate to the operations being performed
- ensure that components are correctly positioned and held securely, without damage or distortion
- update program tool data, as applicable
- position and adjust machine guards
- apply safe working practices at all times
- leave the work area in a clean and safe condition on completion of the activities
- Prepare two of the following CNC optical process machines in readiness for production:
- CNC optical grinding machine
- CNC optical smoothing machine
- CNC special purpose machines
- CNC optical polishing machine
- CNC optical edging machine
- Position and secure workpieces using two of the following workholding methods and devices:
- chucks
- collets
- jigs and fixtures
- fourth axis indexer
- other specific method/device
- Select/mount grinding and polishing wheels for all of the following operations:
- rough grinding/forming
- finish grinding
- polishing
- edging
- Prepare the machine for operation by carrying out six of the following activities, as applicable to the machine:
- pre-setting grinding wheels/spindles using balancing units and setting jigs/fixtures (where appropriate)
- setting grinding/polishing tool datum
- positioning grinding wheels/polishing tools in the correct position in the machine spindle, magazine or carousel
- checking that wheels/polishing tools have a specific tool number in relation to the operating program
- entering all relevant tooling data to the operating program (wheel/spindle position offsets)
- saving changes to the program
- Machine five different types of material from the following:
- germanium
- silicon
- zinc selenide
- zinc sulphide
- lanthanum crowns
- dense flints
- flints/light flints
- barium crowns
- borosilicate crowns
- barium dense flints
- anomalous dispersion flour crowns
- other specific optical material
- Make trial components to prove that the machine is operating to the required specification, and in compliance with one of the following standards:
- BS, ISO or EN standards and procedures
- customer (contractual) standards and requirements
- company standards and procedures
- other accepted international standards