Assessment Title – Mould CNC Machining Time Optimisation & Tool Path Verification
Learning Outcomes – The following module learning outcomes and professional body learning outcomes are tested in this assessment:
Learning Outcome 1) Critically analyse and optimise the machining operations simulation using industrial CAD/CAM package. (EA6M, P10m).
Learning Outcome 2) Demonstrate a good understand metal removal methods of complex freeform surfaces using multi-axis computer numerical control part programming and post-processing. (SM8M, EA5m, P9m)
Learning Outcome 3) Develop an extensive knowledge in identifying the capabilities of the virtual multi-axis machining simulation and verification. (SM9M, G2)
Assessment Task and Specific Terms –
Part A – Mould CNC Machining Time Optimisation & Tool Path Verification
Assignment Brief and assessment criteria: An important part of the CAD process is the development of images in three-dimensional space prior to producing two-dimensional images for manufacturing drawing purposes. In the not too distant future, when computing resources are more readily available, the need for two-dimensional drawings will be eliminated completely as all the generated data sets of co-ordinate points will be held in memory, processed and down-loaded directly to the relevant machine tool prior to manufacture. However, we are dealing with the present day and the need for two-dimensional drawings for manufacturing purposes still exists.
An engineering designer needs to appreciate the advantages and limitations of conventional and computer controlled metal cutting machine tools, to enable products to be economically manufactured. Although the modern trend is towards computer- aided manufacture (CAM) with all the instructions for machine operation fed to the machine as a command signal, each operation has to be broken down and analysed so that the most efficient program can be used by the computer. Therefore a thorough knowledge of basic machining operations is a pre-requisite before CAM can be efficiently utilised.
The main areas which you should focus on in this assignment are the mould design machining optimisation and verification using the mould designed and validated in the first block of this module.
Core & Cavity Mould Machining
Requirements – In this section the students should demonstrate a good understanding of generative machining using NXCAM module of the Siemens PLM solutions package to do the machining of the mould which was designed and validated in the first assignment. The manufacturing technique of the proposed design should be optimised by a clear process of selecting the right machining parameters. This process of optimisation is aimed to reduce the machining time in order to achieve a competitive manufacturing cost of the part and the mould. Machining variables which contribute to this task of machining time reduction (for example; machining too path, federates, step-over etc…) should be properly analysed and approved.
Submissions contents – The students are required to produce a machining setup and simulation of the above moulded part and the part model using NXCAM manufacturing module and optimising the machining time. The students should also demonstrate a good knowledge for the machining process in creating and editing CLDATA, post-processing the generating machining instructions of the cutter location file into a tape file (Machine code data). In order to achieve these, the students are required to demonstrate a fundamental understanding of the following stages of CAM:
1) Prismatic surface machining operations (face, profile and pocket milling).
2) Free form surfaces machining using dedicated methods.
3) Drilling operations and optimisation.
4) Tooling and Machine setup.
5) Operations machining time optimisation & toolpath validation.
6) Generation of the cutter location data (CLDATA) program.
Write a clear and concise report to describe all the process in machining by clearly defining of the machining operations required for the model. Also explain in details all the techniques used in the machining the part and machining time optimisation.
Part B – CNC Machining Virtual Simulation & Verification
Assignment Brief and assessment criteria: In this section the 2 students are required to run the full simulation of the optimised tool path generated in Section – A for the Core & Cavity models. Students should choose the right post-processor and the CNC machine model. A library of a variety of postprocessor and CNC machines/controller are provided and can be accessed in the NX library.
The selected CNC model can be updated to the design specification of the manufacturer if needed.
1. The CNC machine postprocessor capability and machine specification.
2. Generation of the machine code data (MCD) and explain the G and M code.
3. CNC Machine working envelops (X, Y, Z maximum axis travel).
4. CNC max spindle speed & feed-rate.
5. Type of controller.
6. Workpiece/fixture/clamping mounting techniques.
7. Simulation & verification using G/M code.
Write a clear and concise report to describe all the process in machining by clearly defining of the machining operations required for the model. Also explain in details all the techniques used in the machining the part and machining time optimisation.
A critical discussion and evaluation of your findings and also demonstrate a good set of recommendations to the Company.
