Module 3. The CNC process
Embedded Files
Duration: 25 hours
EQF: 4
ECVET: 0,9 C
Activity 1 - Lesson - Tolerances
Step 1: Present students the manufacturing processes and natural variation in manufacturing.
Step 2: Present students what are manufacturing tolerances and their importance in engineering.
Step 3: Present students the standards when writing tolerances.
Step 4: Present students geometric dimensioning and tolerancing. Symbols used and their meaning.
Activity 2 - Classwork - Engineering drawings
Step 1: Present students with a brief summary of activity 1.
Step 2: Show the students a presentation on orthographic drawings.
Step 3: Assign students an exercise in which they receive orthographic projections of different parts and draw an isometric view of the parts.
Activity 3 - Lesson - The CNC process
Step 1: Present students with a brief summary of activity 2.
Step 2: Discuss the CNC process with the whole class as the process starts from the engineering drawings and transforms the stock material into something of value. In general, the CNC process is; Drawings → stock material selection → machining sequence → machine tool choice → work holding device selection → cutting tool selection → plan tool paths → calculate process parameters → operational planning → G Code generation → simulation → part machining → part inspection.
Activity 4 - Class exercise - operational plans
Step 1: Present students with a brief summary of activity 3
Step 2: Divide the students into groups of 2. Each group is given the engineering drawings if a part and they are given 30 minutes to write a standard operational plan (handouts need to be prepared beforehand). Each group presents its operational plan to the rest of the cohort. Discussions are encouraged.
This activity is to be repeated until students can master the planning of simple engineering components.
Activity 5 - Workshop session - the calliper and micrometre screw gauge
Step 1: Present students with a summary of activity 4.
Step 2: Give to the students engineering parts, a digital caliper and a digital micrometer and they are shown how to use them.
Step 3: Show the students a presentation on how to take care of a precision instrument.
Step 4: Give the students an engineering part and its drawing. The student measures it and writes a measurement report. (The tolerances on the part drawing are to be written in such a way that both instruments need to be used).
Tools and materials needed:
a classroom equipped with a computer, audiovisual system (big screen, or projector)
whiteboard
a workshop equipped with a surface plate, electronic calipers and micrometres
some engineering components together with their engineering drawings
Key Learning Outcome(s)
K3 To describe the quality standards and indicators for CNC operations and products.
S1 To interpret the technical-mechanical drawing in CAD.
S4 To check and ensure the quality of the product.
Assessment methodology: Students are assessed individually by 2 assignments. The first assignment (60%) is a home assignment where the student is presented with an engineering drawing and he applies his knowledge of the CNC process to write an operational plan to machine the part from scratch. The second assignment (40%) is done in the workshop where the learner is given a physical part and its engineering drawing and he needs to measure all the dimensions, write a measurement report, and finally accept or reject the part.
Page updated
Google Sites
Report abuse