Machining aircraft components using CNC machining centres
Overview
This standard identifies the competences you need to carry out machining operations, in accordance with approved procedures, using Computer Numerical Control (CNC) machining centres to produce aircraft components. It covers both fixed wing and rotary winged aircraft components. You will take charge of the prepared machine and check that it is ready for the machining operations to be performed. This will involve checking that all the required components and consumables are present and that the machine has been approved for production. In operating the machine, you will be expected to follow the correct procedures for calling up the operating program, dealing with any error messages and executing the program activities safely and correctly.
The aircraft components produced will have a number of different features, including bored holes to a depth and through the workpiece, tapered holes, external diameters, flat faces, square and parallel faces, angular faces, slots, indexed or rotated forms, internal and external profiles, grooves/undercuts, and drilled, reamed and tapped holes to depth and through the workpiece. You will be required to continuously monitor the machining operations, making any necessary adjustments to machine parameters, in line with your permitted authority. 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 activities undertaken and to report any problems with the equipment, tooling, program, materials or activities that you cannot personally resolve, or are outside your permitted authority, to the relevant people. You will be expected to work to with minimum supervision, taking personal responsibility for your own actions and for the quality and accuracy of the work that you produce.
Your underpinning knowledge will be sufficient to provide a good understanding of your work and will enable you to adopt an informed approach to applying CNC machining centre procedures in an aeronautical manufacturing environment. You will have an understanding of the CNC machining centre process and its application and will know about the machine, tooling, materials, machining activities and consumables, in adequate depth to provide a sound background to the machine operation and for carrying out the activities to the required aircraft 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.
Setting up of the machine, its tooling and associated workholding devices are the subjects of other standards.
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
- monitor the computer process and ensure that the production output is to the required specification
- produce machined components
complete the relevant documentation in accordance with organisational requirements
shut down the equipment to a safe condition on conclusion of the activities
- leave the work area and machine in a safe and appropriate condition on completion of the activities
Knowledge and Understanding
You need to know and understand:
- the specific safety precautions to be taken when working with CNC machining centre and equipment
- the requirements and importance of understanding and applying human factors as defined by the regulatory requirements and the potential impact if these are not adhered to
- the safety mechanisms on the machine and the procedures for checking that they are operating correctly
- how to start and stop the machine in both normal and emergency situations
- the hazards associated with working on CNC machining centres (such as use of moving machinery, automatic machine operation, handling cutting tools, lifting and handling workholding devices, hot and airborne metal particles) and how to minimise them and reduce any risks
- the importance of wearing the appropriate protective clothing and equipment (PPE) and of keeping the work area clean and tidy
- the application of a range of CNC machining centres
- where to obtain component drawings, specifications and/or job instructions required for the components being machined
- how to extract and use information from engineering drawings or data and related specifications (to include symbols and conventions to appropriate CAA, FAA, BS, ISO or BSEN 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 interpret 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 (such as program operating and control buttons)
- how to operate the machine, using single block run, full program run and feed/speed override controls
- why you would conduct a full dry run and single block run
- how to make adjustments to the program operating parameters to take account of tool wear
- how to set and secure the workpiece to the machine spindle/workholding device; the effects of clamping the workpiece; and how material removal can cause warping/distortion of the finished workpiece
- 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
- the safe and correct handling and storage of tooling
- 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 tolerances
- the problems that can occur with machining activities and how these can be overcome
- the application of cutting fluids with regard to different materials being machined
- the quality control procedures used, inspection checks to be carried out and the equipment that is used
- 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 use the appropriate documentation (such as job instructions, drawings, quality control documentation)
- adhere to procedures or systems in place for risk assessment, COSHH, personal protective equipment and other relevant safety regulations and procedures to realise a safe system of work
- check that the operating program is at the correct start point
- ensure that machine guards are in place and correctly adjusted
- ensure that materials/components are correctly positioned and held securely without distortion
- check and maintain cutting tools in a safe and usable condition
- ensure that the workpiece is clear of the tooling before starting the machine
- use safe working practices and start-up procedures at all times
- adjust machine settings, as required, to maintain the required accuracy
Produce aircraft components which combine several different operations and cover ten of the following:
- external diameters
- square and parallel faces
- external threads
- tapered diameters
- angular faces
- grooves
- shoulders and steps
- slots
- undercuts
- bored holes
- indexed or rotated forms
- drilled
- tapered holes
- internal profiles
- holes
- flat faces
- external profiles
- reamed holes
- tapped holes
- internal threads
Machine one of the following types of material:
- ferrous
- non-ferrous
- non-metallic
Carry out the necessary checks during production, for accuracy of five of the following:
- external diameters
- thread fit
- internal diameters
- slot or recess width and position
- lengths/depths
- surface finish
- reamed hole size/fit
- flatness of faces
- taper/angles
- squareness of faces
Produce aircraft components within all of the following quality and accuracy standards, as applicable to the operations performed:
- dimensional tolerance equivalent to BS EN ISO 286-1 or BS 1916-1 Grade 7
- components to be free from false tool cuts, burrs and sharp edges
- flatness and squareness 0.001" per inch or 0.025mm per 25mm
- reamed/bored holes within H8
- angles within +/- 0.5 degree
- screw threads BS medium fit
- surface finish 63µin or 1.6µm
Machine aircraft components which comply with one of the following standards:
- Civil Aviation Authority (CAA)/European Aviation Safety Agency (EASA)
- Ministry of Defence (MoD)
- Military Aviation Authority (MAA)
- Aerospace Quality Management Standards (AS)
- Federal Aviation Authority (FAA)
- Aerospace Quality Management Standards (AS)
- BS, ISO or BSEN standards and procedures
- customer standards and requirements
- company standards and procedures
- manufacturers standards and procedures
Complete the relevant paperwork, to include one from the following and pass it to the appropriate people:
- build records
- job cards
- log cards
- aircraft log
- other specific recording method
Scope Knowledge
Values
Behaviours
You will be able to apply the appropriate behaviours required in the workplace to meet the job profile and overall company objectives, such as:
- strong work ethic
- positive attitude
- team player
- dependability
- responsibility
- honesty
- integrity
- motivation
- commitment