Machining components using CNC aspheric glass and diamond turning machines
Overview
This standard identifies the competences you need to carry out the machining of aspheric glass and diamond turned components, using computer numerical controlled (CNC) machines or CNC machining centres, in accordance with approved procedures. You will be required to produce a range of aspheric components of various infra-red and visible materials, which combine a range of different features, such as aspheric form, power, surface roughness, cap height. 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 machining activities undertaken, and to report any problems with the activities, materials or equipment used 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 produce.
Your underpinning knowledge will provide a good understanding of your work, and will provide an informed approach to applying optical machining procedures. You will understand the aspheric glass and diamond turning processes used, 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 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:
P1 work safely at all times, complying with health and safety and other relevant regulations, directives and guidelines
P2 confirm that the equipment is set up and ready for operation
P3 follow the defined procedures for starting and running the operating system
P4 deal with problems within your control and report those that cannot be solved
P5 monitor the computer process and ensure that the production output is to the required specification
P6 produce machined components
P7 complete and store all relevant documentation in accordance with organisational requirements
P8 shut down the equipment to a safe condition on conclusion of the activities
Knowledge and Understanding
You need to know and understand:
K1 how to work safely at all times, complying with health and safety and other relevant regulations, directives and guidelines
K2 the safety mechanisms on the machine, and the procedure for checking that they function correctly
K3 the operation of the machine controls in both set-up and run modes, and how to stop the machine in an emergency
K4 the importance of wearing the appropriate personal protective equipment (PPE), and of keeping the work area clean and tidy
K5 the hazards associated with working on CNC machines and how to minimise them and reduce any risks
K6 the hazards associated with carrying out aspheric lens process operations, and how they can be minimised
K7 the importance of wearing the appropriate protective clothing and equipment, and of keeping the work area clean and tidy
K8 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
K9 how to interpret first and third angle drawings, imperial and metric systems of measurement, workpiece reference points and system of tolerancing
K10 how to read the visual display and understand the various messages displayed
K11 the function of error messages, and what to do when an error message is displayed
K12 how to find the correct restart point in the program when the machine has been stopped before completion of the program
K13 the operation of the various hand and automatic modes of machine control
K14 how to operate the machine using single block run, full program run and feed/speed override controls
K15 how to make adjustments to the program operating parameters to take account of tool wear
K16 the various types of cutting tool used, and how they are located and secured to the machine tool posts, turrets, slides and tool magazine or carousel (including diamond tip tools, diamond abrasive wheels and polishing tools)
K17 how to check that the indexible tooling is in a serviceable condition; and the effects that worn tooling will have on the workpiece surface finish and dimensional accuracy
K18 the lens mounting methods used to set up the workpiece prior to operation, to minimise wedge error, concentricity and astigmatism
K19 the effect of backlash in machines slides, dials and screws, and how this can be overcome
K20 how to handle and store all cutting tools and kit required, safely and correctly
K21 factors which affect the selection of cutting feeds, pressures and speeds required, and the depth of cut that can be taken
K22 the application of cutting fluids with regard to the range of material being machined
K23 how to recognise machine faults, and how to identify when tooling needs refurbishment
K24 the quality control procedures used, inspection checks to be carried out, and the equipment used for this
K25 the issues that can occur with the aspheric lens generating, polishing and diamond turning activities, and how they can be overcome
K26 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 machining activities:
- obtain and correctly interpret the documentation for the type of lens being machined
- 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 correctly adjusted at all times
- ensure that components are correctly positioned and held securely, without damage or distortion
- maintain cutting tools 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 three of the following aspheric lens processes:
- glass aspheric generating process
- diamond turning aspheric process
- glass aspheric polishing process
- diamond turning diffractive/hybrid process
- lybold syrus coating machine
- wordentec wave controlled coating machine
- buhler lion syrus pro coating machine
- other specific equipment
- Produce machined components that combine different operations, and cover six of the following:
- centre thickness
- lens cap height
- lens surface roughness
- lens cosmetic defects
- lens diameter/step feature, angle
- lens power analysis/radius
- lens concentricity
- lens aspheric form analysis
- lens diffractive step height
- transmission
- reflection
- absorption
- uniformity
- coating edge quality
- other specific machined components
- Machine five different types of materials from the following:
- zinc selenide
- zinc sulphide
- optical silicon
- optical glass
- optical infra-red glass 4
- optical infra-red glass 5
- optical infra-red glass 6
- gallium arsenide
- acrylic
- optical grade germanium
- optical thallium ideobromide
- other specific optical material
- During production, carry out the necessary checks for accuracy, to include five of the following:
- lens diameter
- component surface finish
- component cosmetic defects
- centre thickness
- lens bevels/chamfers
- cap height
- component profiles
- surface form error
- angles
- surface/lens power error
- transmission
- reflection
- absorption
- uniformity
- environmental performance in accordance with the specification
- Produce 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