Aims of this work

1. To develop a systematic understanding and critical awareness of sustainable manufacturing systems, system design approaches and planning techniques applied to industry.
2. To enhance the acquisition of analytical knowledge and practical skills gained for analysing a complex manufacturing process or system and their integration using advanced computer design and modelling simulation tools.
3. To explore modelling simulation techniques to help create rapidly and turn innovative ideas timely into systems design, analysis and improvement particularly for a constraint-based production system in a virtual environment.
4. To become an expert in coping with the system uncertainty, examining the system random behaviour, refining the system design, and developing alternative operational management strategies based on the developed virtual prototyping system to a real industrial case study.

Unit learning outcomes

1. Critically appraise a systematic approach with lean thinking and apply it into analysis, planning, design and performance evaluation of a complex production system.
2. Examine modelling techniques and mathematical approaches for capturing the deterministic and stochastic behaviours of manufacturing and prototyping systems

Assessment strategies & instructions

The overall assessment strategy is designed to test problem solving capabilities through a case study in a virtual environment using computer-aided design and modelling simulation tools to satisfy LO1 and LO2, with solutions developed and submitted in a report. Each student is expected to develop their own computer models, which will be checked and questioned by the supervisor as part of the overall assessment.

The report should include the following information:

Unit Title         - Manufacturing System Design

Unit Code       - M32064

Student ID Number

Unit Lecturer:   - Date/Month/Year

1)    Introduction/Background (refers to page 2-3 and your own research work)

2)   Main work (refers to page 3-4)

3)   Discussions and conclusions References (if applicable) Appendix (if applicable)

Assignment

Background

In order to be competitive, modern products must be designed with a view to production methods in which a production system should to be designed in a cost-effective way and the system is able to operate at optimal or near-optimal conditions. Nevertheless, design of a production system can be a complex process and any small change of the system design often makes a significant impact on the overall system performance. In the real-world industry, implementation of the entire production system is often very expensive and the cost of ‘getting it wrong’ can be very high. For these reasons, both system and product designers need to work together to ensure a ‘right first time’ scenario. Virtual prototyping techniques offer a potential solution to the major difficulties involved in design, analysis and performance evaluation of a product and a production system providing a fast delivery of alternative solutions at a minimum of cost. Nowadays, virtual prototyping techniques are commonly used in manufacturing sectors involving some form of computer-aided design and modelling simulation activities.

Assignment & Tasks

This assignment is based on a case study of assembling loudspeakers on a production line that needs to be investigated. A loudspeaker manufacturer has just upgraded its loudspeaker design by incorporating some forged parts with improved magnetic characteristics for the unit, which has additional benefits of reduced part count and part features to facilitate automatic feeding as well as ease of manual assembly. Figure 1 shows the basic structure of a loudspeaker and Figure 2 illustrates what is known as the motor unit assembly together with the voice coil. Figure 3 shows a cross-section through a typical loudspeaker. The assembly of an entire loudspeaker is illustrated in Figure 4 and 5, respectively. The parts in the whole assembly can be grouped into two different types namely:

1.“Soft” parts:

• • dust cap, the diaphragm, the spider and the coil

2.“Hards” parts (These are all in the ‘motor unit’ sub-assembly)

• • pole piece, the magnet and the top plate together with the frame

The proposed manufacturing facilities should as far as possible incorporate automation, however, it is still anticipated that some of the ‘soft’ parts may be assembled manually.  The aim is to produce one loudspeaker every 20s over an 8hr working day and a 5-day week (1440 units/day, 7200 units/week). The speakers can be sold at £5/unit, giving a potential turnover of £36000/week and £1800000/year.

After an initial investigation of the system, data collection and analysis, the following system parameters have been identified and determined:

• Conveyors will be used and it may be 5, 10, 15 or 20 m long.
• Each frame arrives randomly and is loaded in position (manually) in NegExp 18s.
• Each pole plate can be fed/assembled in LogNormal 17s, STD: 5-15%.
• The magnet can be fed/assembled in LogNormal 19s, STD: 5-15%.
• The top plate can be fed/assembled between 15-18s in a uniform distribution.
  • Manual  assembly  of  the spider  and  coil  by  a  worker  takes  a  time  of  35-45s  in a  uniform distribution.
  • Assembly of the diaphragm takes an average time of 18s.
  • Manual assembly of the dust cap takes an average time of 16s.
  • At the magnetisation station: 20s.
  • At the automated test machine (ATM): 10s.
  • Fork-lift trucks may be used at the end of the production line and it may travel at 2m/s.

Figure 1. Loudspeaker construction

Figure 2. Motor unit assembly

Figure 3. Cross-section through a typical loudspeaker

Figure 4. Engineering drawing of the assembly of the loudspeaker together with a 3D computer design assembly

In addition, the following system elements, operational activities and relevant information are suggested below:

1. Each finished loudspeaker will be individually bagged by a worker (s) after the ATM (automated test machine). A robot might be used to pack the finish products into a container. Each container should hold 36 loudspeakers and filled containers should be stacked and wrapped together in groups of 4 before being taken away by a fork-lift truck (s) to the warehouse.
2. Feeders/hoppers can be replenished automatically inside/outside the normal working hours (you decide this). This process involves unpacking parts manually and placing them on a single long conveyor that runs to a centrally located robot which can intelligently pick up correct parts and place these parts on short conveyors running to each feeder. The robot can run with a cycle time of 1.2s. Each worker can place individual parts on the conveyor in NegExp 4s; it needs to keep the number of workers to a minimum. The operating time of this conveyor must also be kept to a minimum since it involves the additional cost of overtime and/or part-time workers.
3. Fully assembled loudspeakers are passed through an automated test machine (ATM) where 1% of inspected units do not comply with specifications and are removed for rework – rework is not part of the study.
4. An eco-friendly and safe shop floor/workshop design is encouraged.

Equipment Reliability

The following information is known about the breakdown and repair of equipment:

TASK

You should attempt to complete the following tasks:

1. Provide a background/knowledge of the loudspeaker-related product and production through a literature study.
2. Create a process plan for assembly of a loudspeaker using ‘pre-manufactured components’. Suggest suitable assembly sequences that would benefit from automated and/or manual operational processes.
3. Produce a drawing incorporating your proposed facility layout design based on the logic sequences of assembly within a boundary (with assumptions in Note) and justify your design by considering such as space utilisation; ease of operations and services; reduction of temporary storage areas or buffer zones, transport/human operator motions; safety; costs etc.
4. Build a full system model using Enterprise Dynamics (ED) software by incorporating 3D objects (if applicable) and all the necessary statistical values; test and verify the functionality of the developed ED models.
5. Design and run suitable experiments with the developed ED models; collect, analyse and interpret the generated simulation data including graphical simulation results to be presented in the report.
6. Evaluate system performance making any improvement that would be most beneficial to the system design and explain why you consider these changes, which may be advantageous.

Note: Make your own assumptions due to any necessary data which may not be given or should not be included in your particular case study. This may refer to such as the availability of factory space, location of stores and so on. You may also consider how your system design may be able to cope with an increase in demands as well as product variances in future.

Your work must be presented and illustrated in a written report. The report should be structured as indicated at page 1 and it should include your own work with the relevant context, drawings and screen- captures and other materials. Please keep your report concisely below 4000 words.

Your work will be assessed according to the “marking criteria” as attached with this assignment. 

Submission

A final report in writing must be submitted via Moodle by 22th January 2021 BEFORE 17:00. The report must be submitted in the MS Word format. A late submission of the report and its assessment will apply in accordance with Academic Regulations, University of Portsmouth, Academic Registry, 2012.