Machining components using CNC optical grinding and polishing machines
Overview
This standard identifies the competences you need to machine glass and infra-red/special material components, using CNC optical grinding and polishing machines, in accordance with approved procedures. You will be required to produce a range of components from various infra-red and visible materials, which combine a range of different features such as surface finish, cap height, diameters, bevels, profiles, parallelism, optical power and form analysis. You will also be required to check and verify finished components, using a variety of metrology equipment, to ensure that they meet the required specifications
You will be required to operate the machine in line with safe working practices and approved procedures, and to continuously monitor the machining operations, making any necessary adjustments in order to ensure that the work output is to the required quality and accuracy. Meeting production targets will be an important issue, and your production records must show consistent and satisfactory performance.
Your responsibilities will require you to comply with organisational policy and procedures for the optical grinding and polishing activities undertaken, and to report any problems with these 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 full 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 applying optical grinding and polishing procedures. You will understand the CNC optical grinding and polishing processes, and their application, and will know about the equipment, materials and consumables, in adequate depth to provide a sound basis for carrying out the activities to the required specification.
You will understand the safety precautions required when working with optical grinding and polishing machines and with the 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
- confirm that the equipment is set up and ready for operation
- follow the defined procedures for starting and running the operating system
- deal promptly and effectively with error messages or equipment faults that are within your control, and report those that cannot be solved
- control the computer process and ensure that the production output is to the required specification
- produce machined components
- complete the required production documentation
- shut down the equipment to a safe condition on conclusion of the activities
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
- the safety mechanisms on the machine, and the procedure for checking that they function correctly
- the operation of the machine controls in both set-up and run modes, and how to stop the machine in an emergency
- the personal protective equipment (PPE) to be worn, and where this can be obtained
- the hazards associated with using CNC optical grinding and polishing machines (such as moving machinery, automatic machine operation, and glass and infra-red/special material particles), and how to minimise them and reduce any risks
- the importance of wearing the appropriate protective clothing and equipment, and of keeping the work area clean and tidy
- 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 the visual display and understand the various messages displayed
- the function of error messages, and what to do when an error message is displayed
- how to find the correct restart point in the program when the machine has been stopped before completion of the program
- the operation of the various hand and automatic modes of machine control
- how to operate the machine using single block run, full program run and feed/speed override controls
- how to make adjustments to the program operating parameters to take account of tool/wheel wear
- the various types of cutting tools used, and how they are located and secured to the machine tool posts, turrets, slides and tool magazine or carousel (including diamond abrasive wheels and polishing tools)
- the optical component mounting methods used to set up the workpiece, prior to operation, to minimise wedge error, concentricity and astigmatism
- how to handle and store all grinding and polishing wheels and tools required, safely and correctly
- the factors that affect the selection of cutting feeds pressures, speeds required and the depth of cut that can be taken (based on workpiece rigidity, machine condition, types of tooling used, material used, finish and tolerance required)
- how wheel wear affects surface finish and dimensional accuracy
- how the various types of material will affect the way the operation is performed
- the application of cutting fluids with regard to the range of material being machined
- how to recognise machine faults and how to identify when grinding and polishing tooling needs refurbishment
- the problems that can occur with optical grinding and polishing activities, and how they can be overcome
- the quality control procedures used, inspection checks to be carried out, and the equipment to be used for this
- 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 optical grinding and polishing activities:
- obtain and interpret correctly the documentation for the type of lens being ground and polished
- 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
- ensure that machine guards/safety mechanisms are in place and are correctly adjusted at all times
- ensure that components are correctly positioned and held securely, without damage or distortion
- maintain grinding and polishing wheels in a safe and suitable condition
- check that the operating program is at the correct start point
- check that the workpiece is clear of the machine spindle
- use safe working practices and machine start-up and operating procedures at all times
- adjust machine settings, as required, during the machining activities to maintain component accuracy
- leave the machine and work area in a safe and clean condition on completion of the machining activities
- Operate two of the following CNC optical grinding and polishing process machines:
- CNC optical grinding machine
- CNC optical smoothing machine
- CNC optical polishing machine
- CNC optical edging machine
- CNC special purpose machine
- Produce optical ground and polished components which combine different operations, and cover five of the following:
- centre thickness
- bevels
- optical form analysis
- surface finish
- component profile
- optical power (radius of curvature)
- cap height
- concentricity
- diameter/step feature, angles
- Grind and polish 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
- During production, carry out the necessary checks for accuracy, to include five of the following:
- centre thickness
- component surface finish
- component cosmetic defects
- component profiles
- bevels/chamfers
- lens diameter
- surface/lens power error
- surface form error
- cap height
- angles
- Grind and polish optical components with dimensional accuracy, form and surface quality, to 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