Problem Statement:

A client has awarded you a project to design an automated assembly system for crayon manufacturing.

Requirements include:

$$ Production rate $=14\mathrm{.}2$ million crayons$/$day

$$ Project budget $=$ $$13$ million

$$ Project delivery $=09$ months

Manufacturing Process:

The steps for manufacturing are:

$1.$ Melt the wax.

$2.$ Mix pigment with wax.

$3.$ Inject uniformly mixed wax into mould.

$4.$ Cool the mixture in the mould.

$5.$ Inspect for crayon defects such as air bubbles.

$6.$ Double wrap the crayons

$7.$ Sort the crayons by colour.

$8.$ Package $24$ different colours of crayons into one box.

$9.$ Package the boxes and ship the crayons.

Figure $4.$ Quality Function Deployment.

Figure $5.$ Quality Function Deployment Example.

Objectives:

The main objectives of this assessment are to:

$$ understand and explain the process flow

$$ identify automation potential

$$ describe and justify the instrumentation required for automation

$$ prepare process and instrumentation documentation

Assessment Tasks:

Task $1$: Identify System Requirements $(10$ marks$)$

You may use Quality Function Deployment $($QFD$)$ or other methods to list out the requirements. You may make some assumptions about some items in QFD$.$

Note: Often the customer will provide a product part list, available budget, desired production rate, delivery time, system up$-$time, and space constraints. For a system integrator, the focus is to understand the requirements from the customers in as much detail as possible. Common requirements include cost, production rate, system up time, and delivery time. Problem statement provides some customer requirements from the crayon manufacturing case study. Your proposed

conceptual design in the proposal should transform these needs into concrete design features that achieve the requirements.

Task $2$: Collect Data $(10$ marks$)$

Provide a list or table of data collected in relation to the design.

Note: An application engineer at a system integration company will want to collect as much detail as possible about the part list, process requirements, and how parts will be presented to the assembly line. For example, will the parts be delivered in a tray or a box? Will they come from another sub assembly line or be shipped from a vendor? Is a machine needed to check the parts before assembly? How big is a lot? How often do you need to refill the part feeder? Are there any pre$-$existing machines that need to be incorporated into the line?

Task $3$: Determine the Assembly Sequence and Cycle time $(20$ marks$)$

Given the required production rate, system up$-$time and part list, an optimum assembly $/$ manufacturing sequence needs to be designed. Draw a precedence diagram $($example shown in Figure $6)$ that should be constructed based on operations precedence relationships; then a line balancing method, such as Largest$-$candidate rule, should be employed to combine work elements into a workstation, and the original cycle time needs to be calculated. After that, balance delay can be calculated to measure line inefficiency and the original cycle time should be compared with the desired cycle time derived from the predicted production rate.

Parallel workstations and$/$or multiple identical production lines will be arranged to reduce default cycle time and$/$or reach the desired production rate. Figure $6$ shows example of parallel workstation and parallel lines arrangements, and Figure $6$ shows the example calculation of cycle time.

The desired workstation arrangement is for each station to have the same operation time and the line inefficiency to be zero.

Figure $6.$ Example precedence diagram.

Figure $7.$ Example cycle time calculation.

Task $4$: Select Assembly Line Components $(15$ marks$)$

This task involves making decisions about $(1)$ the number of machines for each station; $(2)$ the types of machines and machine capacity for each station; $(3)$ types of material handling and transfer equipment needed, $(4)$ types of part feeders and machine tools required, $(5)$ number of operators, and $(6)$ number of work shifts needed to manage the assembly lines. All these factors will affect the overall cost of the proposed design. Therefore, a few alternatives may be proposed. For example, in this crayon manufacturing system, to achieve the desired production rate of $14\mathrm{.}2$ million units per day, the design can incorporate parallel stations$/$machines$.$

Task $5$: Determine Layout of Assembly Line $(15$ marks$)$

There are three common line layouts: inline, U$-$shape and parallel cell configurations. The goal is to reduce material transfer time $($since transfer is not a value$-$added process$)$ and to increase the feedback. Present the layout suitable for the requirements of the design.

Task $6$: Perform Cost Estimation and Analysis $(10$ marks$)$

Cost categories include labour cost, machine$/$equipment cost$,$ materials cost, system development cost, and overhead. Several alternatives may be proposed. Cu

Task $7$:Process Flow Diagram$(PFD)$

Draw a $PFDof$ the design software $,$but $it$ should consist $of$ standard symbols $.PFD$ should include critical instruments required $to$ control and measure the important parameters $in$ different sections $of$ the plant