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ME5608 – ADDITIVE AND NON-CONVENTIONAL

MANUFACTURING PROCESSES

Semester 1 : 2017/2018

Question 1

The following terminology is applied: FDM: Fused Deposition Modelling; LOM: Laminated Object Manufacturing; SLS: Selective Laser Sintering; DMLS; Direct Metal Laser Sintering; SGC: Solid Ground Curing; SLA: Stereolithography Apparatus; LENS: Laser Engineering Net Shaping; 3DP: 3D Printer (from Z-Corp).

(a). Which of the following 3D printing process(es) produce plastic parts?

A. FDM B. LOM C. SLS D. DMLS E. LENS (2 marks)

(b). Which 3DP process was the earliest patented and commercialsed system?

A. FDM B. SGC C. SLA D. DMLS E. 3DP (2 marks)

(c). Which of the following 3DP process(es) can produce rapid tooling for injection moulding?

A. SLA B. DMLS C. SLS D. FDM E. LOM (2 marks)

(d). Which RP process has the highest accuracy compared to the rest?

A. 3DP B. FDM C. LOM D. SLA E. SLS (2 marks)

(e). Which 3DP process(es) can produce multiple colour components?

A. SLA B. SLS C. 3DP D. FDM E. LOM (2 marks)

(f). Which 3DP process(es) can be used to print food (e.g. chocolates, cockiest, etc.)

A. SLA B. FDM C. SLS D. DMLS E. 3DP (3 marks)

(g). At what condition variable slicing has advantage(s) over constant slicing of a 3D model for printing?

A. smaller curvature B. larger curvature C. none of above (4 marks)

(h). Taking the vertical direction as a reference, under which condition from the built features requires supports while in printing:

A. Less than 45 degree B. Greater than 45 degree C. No difference (4 marks)

(i). In the following processes:

A. Chemical-mechanical polishing (CMP), B. Electrochemical machining (ECM),

C. Single-point diamond turning (SPDT), D. Electrolytic In-Process Dressing

(ELID) ELID grinding,

which one(s) can process brittle materials? (4 marks)

Question 2

(a) An SLA-printed part was found distorted and warped after whole day of printing. As a research engineer, you are tasked to resolve this print quality issue. Please propose solution(s) based on process parameters to improve the printed-part quality with a possible process/material model in sketch to justify such approach. (8 marks)

(b) What is the main mechanism in terms of processes or materials to be able to 3D-print metal components without using a high-power laser (above 1 KV)?

(7 marks)

(c) As shown in Fig. 1, an engine blade was removed for maintenance and overhaul. Please propose cost-effective conventional or non-conventional process(es) to restore its engineering functions with required dimension, tolerance and surface finish.

(10 marks)

A B C

Fig. 1 (a) Original blade; (b) blade to be overhauled; and (c) restored blade

Question 3

(a) Explain clearly the various voltage profiles that are possible while doing an EDM process when a transistor based controller is used. If a resister-capacitor based circuit is used how will the voltage profile change?

(7 marks)

(b) You are required to drill a hole of 200 microns on a steel plate of 2mm thick.

(i) List down the various factors that will affect the material removal rate?

(ii) Clearly indicate the effect of electrode wear and material removal rate while changing the various parameters.

(iii) You have the choice of laser, EDM and Ultrasonic machining. Which machining process you would use and why?

(18 marks)

Question 4

(a) What are the key components of an ultrasonic machining (USM) system and explain how you can reduce conicity and improve surface finish in USM?

(6 marks)

(b) You are required to machine a square hole of size 10mm x 10mm on a ceramic block using USM. You have a choice of abrasives, tool shapes and feed rate. Discuss how you will choose and explain the effect of abrasives, tool shape and feed in USM.

(12 marks)

(3 marks)

(c) You are required to machine multiple holes and slots as shown in Figure 2. You have a choice to use Nd-YAG, CO₂ Laser and Excimer Laser. What type of laser you would choose? Explain the effect of feed rate while machining the slot shown in Figure 2.

(4 marks)