lean manufacturing tools and techniques
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Waste Elimination Techniques
SIMPLFY, COMBINE, ELIMINATE First we need to Learn to See the waste. We want to do our work easier, faster, cheaper, better and safer. A basic approach for doing this is to Simplify Combine Eliminate
Standardize Work/Standard WIP
Standardized Work: The best practice method of performing a process to meet your takt time requirements in the most efficient way focusing on value-adding activities.
Standardized WIP: A predetermined maximum amount of work-inprocess allowed between process. In the ideal world its one piece!
One-Piece Flow: The condition in which each work piece passes through the production process by itself. Also known as flow production
Key things to address are: Flow of the process And the waste that stops the flow
Overview of Manufacturing Cells
Definition: Work Cells Self-contained units including several value-adding operations Equipment and personnel arranged in process sequence Perform operations necessary to complete a product or a major production sequence
Principles of Cell Layout Sequential arrangement Counterclockwise flow Machines close together (caution!) Last operation close to first U or C shape
Similar products/processes in a cell to avoid radical change in setup
Basic elements of Cell Design:Three Phases: Understand the current condition Analyze and make the conversion Continuously Improve the process
Understanding the current state: 1. Look at the basic facts about the manufacturing area. 2. Use the Custom Profile Data Collection Forms to understand how the process is currently working. Custom Profile Collection Forms will be reviewed later in this session.
Documenting the Current State:1. Basic facts on the current state (e.g. floor space, WIP, etc) 2. Product focus and quantity 3. Area/Process Mapping 4. Time Observation 5. Takt Time
These five steps of documentation give you a lot of information about how the process currently runs. Next well work on improving it through cell design.
Analyze and Make the Conversion: 1. Determine cell opportunities Review data; consider possible new plans as well as issues Make a plan, do the conversion, document it for operators Make the move, summarize the changes
1. Design the cell
1. Verify (move into cell)
Questions: How many operators does the process require? Could it run with fewer people by eliminating the non-value added work? Is anyone currently cross-trained to operate more than one machine or station in the process? What kind of training might be needed to make a cell run smoothly?
Custom Profile Waste Elimination Data Sheets:
Area Map/Process Map: This form is used to document the process flow.
Process mapping gives another picture of the workflow in an area. How are these forms going to be used at Custom Profile? Theyll be used to flowchart the process in an area. Which will allow you to document the current state.
Custom Profile Area Map Example
Filling out the Area Map/Process Map: Machine/activity layout sequence Process and material flow
Location and Quantity of WIP Safety precautions Quality checks Number and location of employees Caution!!! Complete this in Pencil, the point is to understand flow, not to be an artist! This does not have to be to scale, to speed the process of developing the Area Map.
Raw Material Inventory: Inventory of material that has not undergone processing at a facility. The point of observing raw material is to minimize the amount in the manufacturing area.
Time Observation Sheets: Is a tool for documenting the time required for each operation in the process. Which includes: Waiting time Walking time Loading/Unloading Un-wrapping Installing Etc
Filling out a Time Observation Form: Video tape a minimum of five samples of each operator involved in the process. Trying to obtain this detailed information will be very difficult without videotaping. If possible try to tape different times of the day and different operators performing the same operations. List all the operations in the proper sequence under Description of Operation.
Record each of the five time samples (in seconds) of each operation under #1-5. Take the average and record this number (in seconds) under AVG.
Make sure to record any tasks that dont occur at every cycle. Examples: Machine Set-Ups Un-packaging raw materials Preventative Maintenance Movement of Kanbans etc
Mark down the average number of seconds of each operation which is value added time, Non value added and any machine cycle times. Examples of value added time: Assembling, welding, machining, drilling, any function adding value, Non value added and any machine cycle times. Unwrapping, wrapping, loading, unloading, movement of parts, inspecting, delays, operators watching machines operate, reworking, reassembling, any functions not adding value for the customer.
Examples of non value added time:
Machine cycle time is the time from when the ON button is pushed to when the machine stops its final movement. Loading and unloading are not included.
Custom Profile Time Observation Example
Process Analysis Sheet: Floor Space used (sq. ft.) Total Part Path (Linear Feet) # of People WIP Value added/Non-Value added
Custom Profile Process Analysis Example
Filling out a Work Balance Sheet: 1. Heading Information: Part #: Fill in the part number for the process being documented. Process Name: Fill in the description of the operation being performed here. Analysis Date: Place the date when this work balance sheet was analyzed. Cell: Place the name of the cell that this operation is part of here.
Quantity per shift: This is the amount of the part number listed in 1-a that will be made in a shift. (This number was needed to calculate the Takt Time for the Work Balance Sheet.) TAKT Time: This is the rate at which this part/assembly must be in order to meet customer daily demand. (Gap): This is difference between the operators cycle time and the TAKT Time for the part/assembly. (It must be a positive number if this sequence is to be able to supply the quantity required per day/shift.) Operator: Just as each machine is to be numbered, so are the operators. Place the number of operator here.
2. Sequence Number: Fill in the sequence number assigned to each specific component task that has been assigned to this operator in this column. In as detailed as possible, enter the description of the sequenced activity. Use expressions made up of a present-tense verbs and its direct object. (e.g. press button) Add in the machine number if it is available.
3. Description of Operations:
Time Elements:Manual: Manual Work Time is the amount of operator activity time for this sequence step as shown on the Time Observation Sheet. Auto: Automatic machine cycle time is the amount of unassisted machine cycle time. If the operator must attend the machine this should be consider manual time. Walk: Walking time is the it takes for the operator to move from one station to the next station. You should not distinguish between whether or not the operator is carrying anything or not. Round it off to the nearest second. Leave this space blank if there is no walking time assignable to this step. Total: Enter the total manual and walk times at the bottom of each column.
5. Cumulative Operating Time: (in secs.) Indicate manual work time by a solid line. Indicate machine time by a dotted line. Indicate walking time by a wavy line. Indicate waiting time by a double line. Draw a red line vertically where the TAKT Time is on the chart that is the same value as the TAKT Time in the header marked for this value.
6. TAKT Line:
Cycle Time Reduction/Setup Time Reduction
STR/CTR Set-Up Time: Is the time between the last good part off one model/run and the first good part off the next model/run. Cycle Time: Is the amount of time required to progress from one defined point in a process to another. As long as a beginning and an end are specified. In a later session, we will be covering additional techniques for Set-Up & Cycle Time Reduction.
TPM: Total Productive Maintenance Is a technique for maximizing a production systems efficiency (overall effectiveness). It is a technique that aims at the elimination of all accidents, defects, and breakdowns. Equipment Downtime, Total Employee Involvement