The customer of the project is Danfoss Turbocor. The main concern Danfoss Turbocor wants addressed is the excessive use of hoists. To approach this concern, the team will look for a solution that is applicable to the existing line, with as little redesign as possible. However, Danfoss Turbocor is open to ideas that involve redesigning the production line if it reduces the amount of hoisting in the current line. Figure 2 describes the Voice of the Customer, Danfoss Turbocor.
For this project, the Voice of Customer begins with the reduction of hoist lifting by 75%. To accomplish this goal, the team came up with some expectations: an efficient process, a reliable system, safety in the process, easy to use machinery, and a good positioning of the system.
Finally, the Voice of Customer for this project includes the metric for each expectation. These metrics indicate how the team could positively approach each expectation to meet requirements.
The first metric the team came up with is reduction of waste. For a process to be efficient it has to eliminate anything that does not add value. The other metrics the team came up with were:
reducing breakdowns to increase reliability, ergonomic analysis for the overall safety of the workers, minimization of unnecessary effort by analyzing which lifts could be eliminated from the process, and a well-positioned system to avoid risk and to provide ample space for each workstation.
10 Figure 2: Voice of Customer
Figure 3: Sections of Production Line
R ed u ction of h oi st lif tin g b y 75%
Efficient Reduction of waste Worker idle time
Reliable No breakdowns or jams
Safe Ergonomic analysis
Easy to use Maximize productivity and minimize unnecessary effort
Well positioned system Ample walking and working space
Pre-mechanical
assembly Mechanical assembly Calibration/levitation
Leak Testing Electrical Assembly
Final Testing Area
End-of-line inspection (EOL)
11 Figure 3 shows all the sections of the production line that are included in the project scope. Every compressor is lifted 14 or 15 times, depending on which model, from the start of the pre-mechanical assembly to the end of the EOL inspection. The team will focus on the mechanical section because the workstations are similar in design which allows the team to look for a common solution on each workstation.
The process of hoisting the compressor starts by hooking the compressor to the hoist. By using a pneumatic system and a controller, the compressors are raised and moved from one workstation to the next. The first area included in the project scope is the pre-mechanical area which has two crane lifts; there are four movable hoists to lift the compressor throughout the rest of the line. Using hoists is inconvenient because it can be unsafe for workers, it is a
time-consuming process that adds no value to the final product, it creates opportunities for part damage, and it is expensive.
Figure 4: Fishbone diagram of excessive use of hoist lifting
12 The fishbone diagram in Figure 4 was created to determine the cause of excessive hoist lifting. The major causes in the diagram are divided in four sections: workstation positioning, production line characteristics, convenience of hoist lifting system, and compressor
characteristics. The cause-and-effect diagram helped the team decide that the most probable causes for the problem are: the distance between workstations is too large, workstations are not arranged linearly, compressors are heavy, it is recommended not to manually carry the
compressors because of their shape and size, and different compressor models are produced in the same production line. These causes correspond to the underlined points in the fishbone diagram.
Once the probable causes for the problem were determined, a House of quality (HOQ) matrix was created. The HOQ matrix is used to understand what the customer wants, and then translate it into design requirements. This diagram is important to the project because it helps the team understand what specific aspects of the production line should be measured and analyzed.
13 Figure 5: House of Quality
The customer requirements used in the HOQ are the same as those in the Voice of customer tree in Figure 2. Every technical requirement is related to a cause of the problem determined from the fishbone diagram. The rate of production corresponds to the amount of compressors that will travel from pre-mechanical assembly to EOL inspection within one hour.
This technical requirement measures the efficiency of the production line. The movement time between workstations is the amount of time between hooking the compressor and unhooking it in the next workstation. The distance between workstations is the length between workstations in the TT-Model line. Weight-carrying capacity is the amount of weight that can be carried by the object used to move the compressor between workstations. Ergonomic analysis of the method
14 used to move the compressor between workstations is the evaluation of safety and efficiency from the method used. Above each technical requirement in the HOQ matrix there is a space.
This space is used to show what would be optimal for each technical requirement. If there is an arrow pointing upwards, it is optimal if the technical requirement is maximized, if there is an arrow pointing downwards, it is optimal if the technical requirement is minimized, and if there is an X, it is optimal if the technical requirement is conducted.
The importance number given to each customer requirement was based on what Brian Conklin and Bruce Barnett considered important for the production line. The relationship between every customer requirement and technical requirement is catalogued in four categories that have a preassigned value. The relationship categories with their respective values are: strong (9), moderate (3), weak (1), and none (0). Every category value is multiplied by the importance number of the customer requirement in the relationship. After that, all the multiplied values for each technical requirement are added together to get an importance value for each technical requirement. Finally, each technical requirement is assigned a priority number based on how high its importance value is. The priority number shows how relevant a technical requirement is to the project.
The top part of the HOQ matrix is used to compare the correlation between technical requirements. This is important because it helps the team understand the effect incrementing a technical requirement has on the other technical requirements. The correlation between technical requirements are catalogued in five different correlation categories: strong positive, positive, negative, strong negative and no correlation. The correlation between rate of production and movement time between compressors is strongly negative because the longer it takes to move a
15 compressor between workstations, the lower the rate of production. The correlation between rate of production and distance between workstations is negative because the higher the distance between workstations, the lower the rate of production. The correlation between rate of
production and ergonomic analysis is positive because if the analysis is conducted, it is likely to increases the efficiency in production. The correlation between the movement time between workstations and the distance between workstations is strongly positive because the larger the distance, the longer it will take to move the compressors. The relationship between the
movement time between compressors and ergonomic analysis is positive because if the analysis is conducted compressors are likely to be moved faster. None of the other technical requirements have a correlation.
The direction of improvement for each design requirement is represented by three categories. These categories are to maximize, minimize, and target the design requirement. The rate of production is placed in the maximize category because it is better if the compressors can be produced faster. The movement time between workstations and the distance between
workstations design requirements are placed in the minimize category because if these are minimized the opportunity for injury or part damage is reduced. The weight-carrying capacity is placed in the maximize category because the system will be better if it can carry more weight.
The ergonomic analysis was placed in the target category because making sure the system is ergonomically safe will improve its quality.
The analysis of the HOQ shown in Figure 5 leads to the conclusion that the ergonomic analysis is the most important technical aspect of the project and should be the focal point of
16 measurements. The second most important technical requirement is measuring the weight
carrying capacity of the proposed alternative to hoist lifting.
In order to visualize what needed to be accomplished for the Control phase, the team created a work breakdown structure. This allowed the team to break up what needed to be accomplished and divide up each part of the phase. Following creating the WBS, the team broke up the tasks into a responsibility assignment matrix. This allowed the team to assign each task and also have another teammate accountable to check up on the individual responsible. This helped provide the team with a system of checks and balances to ensure everything was being completed. The responsibility assignment matrix is shown in Figure 7.
Figure 6: Control Phase Work Breakdown
17
Figure 7: Responsibility Assignment Matrix
18