Six Sigma Root Cause Analysis and Waste Elimination

Put the steps in the 5 Whys process in the correct order.

1. Choose a cause and ask why the problem is happening. 2. Ask: "Why does this occur?" List possible causes.. 3. Investigate potential causes and use data to eliminate some. 4. Establish why the remaining cause is happening. 5. Determine the actionable root cause of the problem.

Place the steps of performing an FTA in the correct order.

1. Identify the top event. 2. Identify potential causes. 3. Identify root causes. 4. Prioritize causes. 5. Identify countermeasures.

Put the steps of performing a fault tree analysis in order.

1. Identify top event. 2. Identify event causes. 3. Identify root causes. 4. Prioritize causes. 5. Identify countermeasures.

Sequence the steps in the 5 Whys process.

1. Select a cause and ask yourself why the problem exists. 2. List possible causes why the problem is occurring. 3. See whether you can eliminate any causes using data. 4. Uncover why the remaining cause is happening. 5. Establish the root cause of the problem that is actionable.

The finishing department at a clothes maker is responsible for adding buttons, snaps, and rivets to a line of designer jeans. Supplies are provided to the tailor by an upstream workstation. Sequence the steps in kanban-pull for this process.

1. The safety stock level of rivets required is calculated as 600 (50 units at 12 rivets per unit). 2. The lead time for replenishment of materials is one hour. 3. To fill orders from customers, the batch size is fixed at 1,500 units. 4. The replenishment order is checked and adjusted before it is entered on the kanban card.

A workstation team at a manufacturer of wind turbines is responsible for putting together the arm attachment component. Sequence the four basic steps that the team follows to configure a kanban-pull system.

1. The team determines it will need a five-day supply of materials to hold in reserve as safety stock. 2. Taking manufacturing and transport time into account, the lead time for ordering blades is determined to be one week. 3. The team calculates it will need to produce a run of 90 units to fulfill customer demand. 4. The team checks its calculations and adjusts the materials request.

A Green Belt working for a pet food manufacturer is working on a kanban-pull process for the mixing and production of a premium brand of kibble. Sequence the four basic steps in kanban-pull as followed by the nutritionist at his workstation.

1. To account for variation in market demand, he determines that the level of safety stock should last one week. 2. The replenishment lead time for ingredients is calculated to be no more than three days. 3. To meet demand, he determines each batch will take one day and produce 2,000 bagged units. 4. The replenishment orders are checked and adjusted before they are sent to the supplier.

Match standard work documents to their purposes. Combination sheets Capacity charts Task and training manuals Standard operating sheets Standard worksheets

Combination sheets - Record manual, walking, automatic, and waiting times in a chart. Capacity charts - Chart the output of the machines involved in a process. Task and training manuals - Used as reference for procedures, equipment layouts, safety standards, cycle times, and quality checks. Standard operating sheets - Communicate standard timings and procedures and relay accurate, up-to-date information. Standard worksheets - Visually represent each work sequence.

Standard work is another method that helps reduce waste within a process. Match each element of the standard work process to its purpose. Combination sheets Capacity charts Task and training manuals Standard operating sheets Standard worksheets

Combination sheets - These documents record manual, walking, automatic, and waiting times for a process or procedure. Capacity charts - These documents express what a machine used in a process should be capable of. Task and training manuals - These documents are instructions for how to implement the process. Standard operating sheets - These documents describe the interaction of a worker with equipment and tools. Standard worksheets - Fields in this document include cycle time, work sequence, and standard inventory for a workstation.

Which characteristics apply to the kanban-pull method for reducing waste?

For the system to work, material needs to flow at a steady rate in a fixed path. It helps reduce inventory. It's an inventory control system that indicates when material or stock is needed by a process. A customer order is the signal that gets the process moving to make parts and materials. It helps a business keep minimal amounts of inventory. An advantage is that businesses can avoid overproduction by regulating how much material is moving through the process at any time.

An important task for Six Sigma teams is finding the true root causes of problems. Which statement most accurately describes the general process for doing this?

Generate a list of possible causes, group them, and then prioritize the list to determine which ones require immediate attention.

Poor communication at a training company often results in rework. Printing costs are excessive, and redundant editing and signoff tasks result in long development cycles. Which strategies can the company use to reduce or eliminate waste?

Improve training to reduce the need for so many sign-offs and edits, which result in waiting and overprocessing. Ensure better communication flow by having teams meet daily for updates to reduce overproduction and overprocessing. Use kaizen to streamline the editing process and to find ways to reduce overprocessing.

Workers are regularly searching for tools, navigating around obstructions on the shop floor, and redoing work because equipment settings aren't set right in a manufacturing plant. By which means can waste be reduced or eliminated?

Install equipment poka-yoke to limit defects in components and to eliminate the need for rework. Organize the work space more efficiently by correctly storing items used and maintaining order, as well as by following standard procedures. Ask suppliers to move away from bulk discounting and to deliver needed supplies only.

One of the commonly used tools for root cause analysis is the fishbone diagram. Which statements accurately describe this tool?

It's also known as the cause-and-effect diagram because it helps uncover all the potential causes related to a particular effect. The first step in creating the diagram is to develop a problem statement that the team agrees on.

In its efforts to reduce waste, a Six Sigma team is assessing the activities a laundry detergent manufacturer carries out. Match the examples of activities to their types. More than one activity may match to each type. Nonvalue-add activities Required nonvalue-add activities Value-add activities

Nonvalue-add activities - A forklift operator moves chemical ingredients to the mixing area. Stock is stored at the warehouse while awaiting delivery to stores. Required nonvalue-add activities - A chemist tests detergent powder to ensure it meets regulatory requirements. A computer operator prepares a production report. Value-add activities - Automated equipment packs detergent into cardboard cartons. A technician adds perfume to the detergent powder mixture.

A Six Sigma team is assessing the activities conducted at a travel agency's call center. Match each activity to its type. More than one activity may match to each type. Nonvalue-add activities Required nonvalue-add activities Value-add activities

Nonvalue-add activities - Insurance forms are filled in per insurer's regulations. Copies of daily records are made and stored in files. Operators move from their desks to retrieve printed documents from the printer room. Required nonvalue-add activities - Commissions are calculated according to sales made by operators. Value-add activities - Operators greet customers in a friendly way. Operators book flights and accommodations using an online application.

A Six Sigma team at a frozen foods factory is assessing the factory's activities and processes. Match examples of activities to their types. Each type may have more than one match. Nonvalue-add activities Required nonvalue-add activities Value-add activities

Nonvalue-add activities - Transport food to a freezing area. Inspect packaging to ensure the company logo is correctly displayed. Required nonvalue-add activities - Calibrate steam chamber to meet food regulation standards. Calibrate slicing machines to cut vegetables to the desired size. Value-add activities - Slice raw vegetables into bite-sized pieces. Cook raw vegetables in a steam chamber.

A legal consulting firm notices that its employees waste time searching for documents on messy desks and in filing rooms. Hard-copy case files are transported in carts from room to room. In which ways can the firm reduce or eliminate waste?

Organize desks and filing systems to reduce excess motion. Set up teams working in parallel on different aspects of a single case to minimize waiting. Set up a centralized electronic database accessible to all employees to minimize transportation of paper.

Poka-yoke focuses on preventing mistakes before they happen by eliminating the opportunity for error and detecting the potential for error in existing processes. Match each type of poka-yoke to its example. Screening Checklists Signaling Control methods

Screening - A vending machine company designs its machines to accept only legal coinage. Checklists - Before beginning each shift, an operator uses a form to account for each piece of equipment. Signaling - At a furniture manufacturer, a sensor counts the number of times a drill bit is used and a light signals the operator when the bit needs to be replaced. Control methods - Each step of a perishable-food packaging machine cycle relies on a timer. If each step is not performed within the required time, then the machine will stop until the food is discarded.

An auto manufacturer has incorporated a number of poka-yoke devices into its manufacturing process. Match each type of poka-yoke to its example. Screening Checklists Signaling Control methods

Screening - An industrial lathe is designed so it will not turn on unless the belts are all properly tightened. Checklists - A simple form is used to make sure each car has been thoroughly cleaned after manufacture. Signaling - Workers use screwdrivers that check the tightening torque and beep when bolts are overtightened. Control methods - Rapid assembly robots shut down if they are not working properly, to avoid rendering defective products.

Poka-yoke, or mistake proofing, helps reduce waste in the workplace. Match each type of poka-yoke to its example. Screening Checklists Signaling Control methods

Screening - Bits on an industrial drill are designed to fit only if they are inserted correctly. Checklists - A delivery company uses a simple form to mark that all vehicles are present and accounted for at the end of each day. Signaling - A buzzer sounds when a machinist has drilled the required number of holes in an auto part. Control methods - A workstation at a manufacturing plant uses sensors to determine if each step in a process occurs. If a step is missed or done out of sequence, the machine stops.

Which actions are associated with the 5S tool for reducing waste in the work environment?

Scrubbing or cleaning the workspace. Sustaining improvements. Sorting out what's needed. Standardizing the practices for sorting, straightening, and scrubbing. Straightening or organizing the workspace.

5S is a practical method for eliminating waste in the workplace. Match each 5S step to its example practice. Sort Scrub Standardize Sustain Straighten

Sort - Inspect and list items that need to be disposed of, donated, or relocated. Scrub - Assign individual responsibilities for cleaning the workspace. Standardize - Determine regular inspection methods and routines. Sustain - Reward compliant behavior. Straighten - Decide at which step in the process each needed item best fits.

Match each technique in the 5S approach to its associated practice. Sort Scrub Standardize Sustain Straighten

Sort - Remove unneeded items from the workspace. Scrub - Find sources of dirt and grime and introduce conditions for correction. Standardize - Record 5S activities and incorporate them into the normal work routine. Sustain - Monitor adherence to each of the 5S steps. Straighten - Determine the optimum locations for tools, equipment, inventory, and supplies.

Implementing 5S helps remove waste from the work environment through better organization. Match each 5S step to an example of the type of activity that might take place. Sort Scrub Standardize Sustain Straighten

Sort - Remove unneeded items from the workspace. Scrub - Provide instructions and training for cleaning and maintenance of workspace, tools, and equipment. Standardize - Develop consistent routines for cleaning and checking. Sustain - Establish and perform regular evaluations of each step and determine areas for improvement. Straighten - Mark aisles and areas for movable equipment and boxes.

A Six Sigma team is investigating why a training session didn't have the desired results. The team decides to create a fishbone diagram to help analyze the problem. Which statements describe effective ways to use this type of diagram?

The team develops an agreed-upon problem statement at the beginning - namely, training efforts have not increased employee knowledge of products. The team brainstorms the causal factors influencing the problem, including lack of time, unprepared instructors, and lack of hands-on practice. Also called the Ishikawa Diagram, it helps find all the potential causes for one specific effect or problem. Causes are generated during a brainstorming session and then grouped by main cause and contributing factors.

As a Six Sigma Green Belt, you must be able to identify different types of waste. Match the types of waste to their examples. Unnecessary inventory Transportation Overprocessing and defects Excessive motion Waiting Overproduction

Unnecessary inventory - Excess raw material had to be stored until needed. Transportation - Raw materials were moved from the receiving area to the storage room to the factory floor. Overprocessing and defects - An overly complex procedure for putting content onto the company's web site results in several errors. Excessive motion - Employees must walk fairly long distances to fetch various tools and components. Waiting - The factory line at a candy manufacturer is held up because a key ingredient has not arrived. Overproduction - A factory manufactured 500 switches when only 300 were ordered.