CNC Milling

WorldSkills Occupational Standards (WSOS)

Occupation description and WSOS

The name of the skill competition is

CNC Milling

Description of the associated work role(s) or occupation(s)

CNC Machining has become one of the most important current machining processes in modern industry. Parts are made for household equipment, telecommunications, cars, ships, airplanes, oil rigs, bridges, aerospace etc. Customers come from virtually every sector. It covers a broad variety of machining processes, such as grinding, welding, electrical discharging, milling, and also turning or turn-milling. The CNC Machinist dictates the entire production process through the choice of setup, tools, and movements through their programming. Once correctly programmed and set up, these machines can produce almost any shape and can repeat the process infinitely. This offers great advantages for quality and efficiency.

CNC Milling machines use versatile manufacturing processes that create precise and complex parts from a variety of materials, using multi-axis and a variety of techniques (face, form, profile milling, ramping, contouring, jigs, and fixtures). CNC Mills can produce almost any shape and any part, especially with CNC mill-turn machines. These machines can perform both turning operations (rotating the workpiece against a cutting tool) and milling operations (rotating a cutting tool against a stationary or rotating workpiece) within a single setup.

Different requirements and demands are required for each customer application. Therefore, workpieces are made of different materials with different properties and different geometries, tolerances, and surface qualities. To provide the machinist with all the information they need, there is a technical drawing (finished part drawing) in digital or paper form for each workpiece. The digital data of the required part can be imported in software, which makes it a lot easier to achieve the desired geometry. However, the machinist must thoroughly check if and how the geometry can be achieved.

Machining starts with deciding how best to produce the part. There are many ways of doing this, like welding, milling, casting, and 3D Printing. One very important method is CNC Milling. A CNC mill is a very accurate computer-driven machine, where cutting tools, controlled by a program, are moved to cut away excess material to result in the expected workpiece. The CNC Milling machinist receives the technical drawing and uses the mill in many ways to find solutions to build the part. The CNC machines are able to achieve accuracy below ten microns, which is six to ten times thinner than a human hair.

The CNC Milling machinist uses a computer to communicate the toolpaths, including speed, depth of cut, and cutting particulars to achieve the desired shape. They must also set up the mill with all the necessary clamping devices, support devices, and cutting tools. These tools can cut almost every material (stainless steel, plastic, soft steel, aluminum, bronze, and so on). But the machinist must choose well to avoid temperature variations, tool wear, and vibration. Those factors influence the product and can result in poor quality.

When the machine starts cutting material, the machinist must ensure that all dimensions exactly fit the workpiece specifications. This may require some modifications, and very accurate inspection tools must be used. Once the machine is set up, the CNC Milling machinist also monitors and optimizes the processes to achieve even faster and better results for all the following parts. When making very complex parts, the CNC Machinist must read and understand drawings and transfer the data to the control of the machine.

Beyond this, CNC Milling represents one of the enabling technologies of Industry 4.0. CNC machines are essential elements of integration within the factory of the future, being fully connected to digital systems that allow real-time monitoring, adaptive control, and integration with production chains. Increasingly, these machines are combined with Artificial Intelligence (AI) to support the creation and optimization of their programming through CAD/CAM systems, enabling even greater automation, efficiency, and flexibility.

Problem-solving strategies, logical thinking, a high sense of precision, and the understanding of technical communication are the basic requirements for the CNC Mill Machinist.

The WorldSkills Occupational Standards (WSOS)

General notes on the WSOS

The WSOS specifies the knowledge, understanding, skills, and capabilities that underpin international best practice in technical and vocational performance. These are both specific to an occupational role and also transversal. Together they should reflect a shared global understanding of what the associated work role(s) or occupation(s) represent for industry and business (www.worldskills.org/WSOS).

The skill competition is intended to reflect international best practice as described by the WSOS, to the extent that it can. The Standard is therefore a guide to the required training and preparation for the skill competition.

In the skill competition the assessment of knowledge and understanding will take place through the assessment of performance. There will only be separate tests of knowledge and understanding where there is an overwhelming reason for these.

The Standard is divided into distinct sections with headings and reference numbers added.

Each section is assigned a percentage of the total marks to indicate its relative importance within the Standards. This is often referred to as the “weighting”. The sum of all the percentage marks is 100. The weightings determine the distribution of marks within the Marking Scheme.

Through the Test Project, the Marking Scheme will assess only those skills and capabilities that are set out in the WorldSkills Occupational Standards. They will reflect the Standards as comprehensively as possible within the constraints of the skill competition.

The Marking Scheme will follow the allocation of marks within the Standards to the extent practically possible. A variation of up to five percent is allowed, if this does not distort the weightings assigned by the Standards.

WorldSkills Occupational Standards

Section		Relative importance (%)
1	Work organization and management	10
	The individual needs to know and understand: The CNC manufacturing process as an enabling technology of Industry 4.0 The scope and limits of the workshop and the workspaces Standards for the environment, safety, hygiene, and prevention of accidents How and when to use safety equipment, such as first aid kits and fire extinguishers Types of energy supplies for CNC milling machines and their sustainable management Basic machine maintenance (coolant-maintenance, machine-lubrication, settings etc.) Methods for ensuring the maintenance of machinery to promote efficient and reliable working Machine Accessories such as clamping devices, tailstock, and part-catching devices The use and care of the available computer operating systems Programming, setting, and operating of CNC milling machines with live tooling and multiple axes CNC-programming systems (Din-ISO (G-Code), CAM software); Principles of technical design and process planning Properties of ferrous and nonferrous materials Mathematics, especially calculations in trigonometry Principles of cutting- and chip-removal technology The importance of effective communications and teamwork The use of machinery-handbooks, datasheets and manufacturers’ operating instructions The calibration, accuracy and use of measurement- and gauging tools.
	The individual shall be able to: Organize the workspace for optimal safety and performance Check the condition and functionality of the workspace, equipment, tools and materials Interpret and apply quality standards and regulations Promote and apply health and safety regulations and best practice Set up and operate CNC mills safely and environmentally well managed (e.g. in use of energy) Use computer related professional software Perform manual interventions to achieve excellence in manufactured components Apply mathematical and geometrical principles for programming processes Select and apply appropriate cutting technology for the material, equipment and cutting tools provided Interpret and apply manufacturers’ instructions Find appropriate data in handbooks, tables, and charts Develop creative solutions to complex design or technical challenges Exchange information with technical and non-technical personnel and customers.
2	Interpret engineering drawings	10
	The individual needs to know and understand: ISO 1 and/or ISO 3 (European and American) drawing representations Technical terms and symbols used in drawings and plans Standards, standards symbols, and tables Technical drawing legends.
	The individual shall be able to: Interpret engineering drawings and apply to specifications Locate and identify dimensions of features Locate and identify surface finish requirements Locate and identify geometric specifications Locate and identify assembly specifications of parts Make 3D mental representations of the parts Identify the materials that are to be used Identify critical sequences (with a high possibility of damage or unsafe practice) and develop appropriate approaches.
3	Process planning	10
	The individual needs to know and understand: Types of machining tools used in CNC milling The importance of good planning for reliable milling operations The procedures and calculations required for scheduling time with software and machinery Successful timing of selected sequences Identification of critical sections The behaviour of machines, clamping devices, materials, tools and machine accessories in different cutting processes Methods and techniques for work holding Methods to avoid crashes or collisions during set-up, tool proving, and operation for the selected sequences Appropriate milling and measuring processes.
	The individual shall be able to: Find solutions using the capacities of the workshop environment, and according to the required work (size of batch, complexity) Identify the appropriate milling and measuring processes Identify and prepare the best work holding methods Identify, prepare, and calibrate appropriate measuring tools Identify and prepare appropriate cutting tools and inserts Identify critical sections (with a high possibility of damage or unsafe practice) and identify alternatives or safe practice to avoid accidents or damage Find innovative ways of using the environment to solve technical issues Explore and apply innovative tooling options Weigh each solution and choose the best (considering context, speed, safety, price, and sustainability) Plan the operations and sequences (milling strategy) based on specified data Manage time so that activities are carried out as planned.
4	Programming	10
	The individual needs to know and understand: CNC Programming as the creation of a logical process plan Different methods and techniques to generate programmes (manual, CAM etc.) CAM system programming and the techniques of part- and tool-modelling Cutting-effect (temperature, bending, force etc.) on: Geometry of the work piece design Work holding devices Tool holding devices Machine-accessories The selection of cutting tools for required material and features Mathematics (especially trigonometry) Speeds and feeds for different materials and tools and work holding devices The basis for choosing correct postprocessors The generation of G-Code Dialoguing with the CNC milling machine The proper use of canned cycles to programme work piece features (classical features as well as driven-tool features).
	The individual shall be able to: Select the best methods according to the production type and part specifications Use skill specific software and related hardware Generate programs using CAD/CAM systems Create or edit programmes directly on the machine-control Edit running programmes in CAD/CAM and reload to the machine-control Simulate machining strategies and perform optimizations.
5	Metrology	5
	The individual needs to know and understand: Chip removal behaviour of provided materials and tools The temperature-related behaviour of provided materials, tools and machine-accessories The properties, uses, and handling of ferrous and non-ferrous materials The effects of cutting force on material, clamping-devices, tools, and machine accessories The range of tools and gauging instruments and their applications The influence of temperature on measurements.
	The individual shall be able to: Identify and design the functional parameters for operating on the CNC milling machine Select appropriate measuring or gauging instruments Calibrate measuring tools Use selected tools to make measurements on all features of the products Use the measurement probe available on the CNC machine, correctly.
6	Set and operate CNC milling machines	50
	The individual needs to know and understand: The different steps that lead to the setup of the milling machine The different modes of machine operation The appropriate power up and Initializing sequence of CNC milling machines The proper manipulating of CNC milling machines Mounting tools and setting tool parameters The modification of clamping devices, such as jaws, dual spindle etc. The transfer of CNC programs to machine control, using provided software, memory devices, or wireless technology The testing of programs (simulation, dry run etc.) The correct, efficient and safe clamping of workpieces Settings of work shift and tool shift offsets The safe running of CNC procedures Stopping and restarting cycles Emergency stopping.
	The individual shall be able to: Identify and designate the different machining process on a CNC milling machine Follow their selected process strategies Appraise and follow a given process-strategy when using external CNC-programs Upload generated CNC programs to CNC milling machines and perform test runs Identify and designate the different machining processes on CNC milling machines Mount and align selected tools Mount and align selected work holding devices Mount and align selected accessories (Tailstock, Parts-catcher, etc.) Set measures to avoid vibration in machining sequences and generate optimum milling Perform a range of machining operations, including: Facing Roughing Drilling cycles Boring cycles Thread milling canned cycle 3D machining operations Apply efficient burr-removal techniques on work pieces Optimize machining strategies Quickly react to problems and emergencies Obtain dimensions, geometries, surface roughness etc. Make all necessary corrections to get the final part to conform to the blueprint Report health, safety, and environmental issues to the appropriate personnel Report equipment failures to the appropriate personnel.
7	Finalize work pieces	5
	The individual needs to know and understand: Appropriate procedures with documentation The importance of completing work pieces to the required standard within one’s capabilities The circumstances in which referral should be made to other appropriate personnel Policies and good practice for the disposal of waste material.
	The individual shall be able to: Clean and deburr parts Make final optical and measurement checks Perform manual finishing operations and cleaning of the workpiece using hand tools Deliver parts, drawings and digital memory devices to the appropriate locations and/or personnel as required by the organization Dismount tools, clamping devices and machine accessories Clean the machine and workplace Dispose of waste material according to the policies in place and good practice Set each environment to readiness for the next job Document and save CNC Programs, work-holding and tooling information etc., following each organisation’s process Complete and deliver reports as required, including concerns and recommendations for improvements and good practice.
	Total	100

References for industry consultation

General notes

WorldSkills is committed to ensuring that the WorldSkills Occupational Standards fully reflect the dynamism of internationally recognized best practice in industry and business. To do this WorldSkills approaches a number of organizations across the world that can offer feedback on the draft Description of the Associated Role and WorldSkills Occupational Standards on a two-yearly cycle.

In parallel to this, WSI consults three international occupational classifications and databases:

ISCO-08: (http://www.ilo.org/public/english/bureau/stat/isco/isco08/)
ESCO: (https://ec.europa.eu/esco/portal/home )
O*NET OnLine (www.onetonline.org/)

References

The WSOS appears most closely to relate to: Milling and Planing Machine Setters, Operators and Tenders:
https://www.onetonline.org/link/summary/51-4035.00

or Milling Machine Operator:
http://data.europa.eu/esco/occupation/a1c9f8b7-c4ce-4b15-ac3c- 3378c300d8f2

These links also enable a review of adjacent occupations.

ILO 7223.

The following table indicates which organizations were approached and provided valuable feedback for the Description of the Associated Role and WorldSkills Occupational Standards in place for WorldSkills Lyon 2024.

Organization	Contact name
GBR Mechanico Pte Ltd	Davizon KK Yee, Director
Japan Organization for Employment of the Elderly, Persons with Disabilities and Job Seekers	Naomasa Ishii, Machining Training Instructor
MAN energy solutions	Matthias Wiedenmann, Team Leader Equipment Production
Robert Bosch	Fábio Silveira, Training Manager
RUAG AG	Raffael Widmer, BBV Polymechanics
SolidCAM Ltd.	Michal Ševčík, Global Education Manager
Tungsten Carbide Tool Factory Paul Horn GmbH	Jannik Biesinger, Instructor
Walter AG	Michael Kaltenbach, R&D Manager Roundtools Milling