Product Family Turnover Rate, Every Product Every October 27, 2007
Posted by Lawrence Loucka in : Definitions, Lean , 1 comment so far
In mixed model fixed repeating scheduling we want to balance run time and changeover time, that is we want to determine how much to run and the time interval between successive runs. Some refer to this a Every Product Every Interval (EPEI). Here’s the math:
A = Available Time (*% Uptime)
L = Production Load = sum run time for all members of the product family ( average demand for product i * cycle time for product i). Note that this doesn’t include changeover time.
C = Total Changeover Time = sum of changeover times needed to accomplish one changeover for each product in the family
PFTR = (A - L) / C
Example:
Available time is 2 shifts of 8 hours and 10% unplanned downtime
We have 4 products in the family with average daily demand of 14 A’s, 6 B’s, 4 C’s and 2 D
Cycle time for a unit is the same for all products, and is 30 minutes per piece
Changeover time between each product is 60 minutes
So:
A = 2 shifts/ day * 8 hrs/shift * 0.90 = 960 minutes * 0.90 = 864 minutes/day of effective available time
L = (14 + 6 + 4 + 2) * 30 minutes per piece = 780 minutes/day of production load or run time
C = 4 products * 1 hour changeover = 4 hours = 240 minutes/family
PFTR then is (864 - 780) / 240 = 0.35 or a EPE Interval of 2.85 days.
Our run sizes would be 40 A’s, 17 B’s, 12 C’s and 6 D’s.
Here’s another example:
Number of different parts running through an injection molding center = 20
Setups take 1 hour between each mold change
20 days in a month, 16 hours in a day
Available Time = 20 day/month * 16 hours /day = 320 hr/month
Load or run time = sum or all cycle times to produce a month of demand = 280 hrs/ month
Time available to do change overs = 320-280 = 40 hours a month
Number of cycles per month = 40/20 = 20
Repeat Interval = 10 days, so make 10 days worth of each part every 10 days.
Muda in the Warehouse September 25, 2007
Posted by Lawrence Loucka in : Consulting, Definitions, Lean, Lean Sigma, Logistics, Supply Chain , add a comment
Although created in the manufacturing environment of Toyota by Taiichi Ohno, the Seven Wastes can be found almost everywhere, if you learn how to see them. Here’s some lean thinking for the warehouse:
Overproduction - Think about the consequences when consumers, retailers, wholesalers, distributors, and manufacturers justify "just in case" or Murphy stock as a hedge against unplanned demand. Money, time, people, physical assets, the environment have all been tied up for something that isn’t needed.
Waiting - the ‘hurry up and wait’ of trucks sitting idle or drivers killing time awaiting their turn at the dock, or DC workers or lifts standing by waiting for tools, instructions, materials to arrive or to be taken away. Waiting comes from poor layout, lumpy demand, system batching. Then once the blockage is cleared we hustle.
Defective Product or Service - from picking errors, incorrect order quantities, misplaced stock to shipping on the wrong carrier or the wrong mode these errors consume resources of time, people and materials to no useful end. Worse yet, additional resources, often 2 or 3 times the original, are usually needed to correct the error.
Overprocessing - how about dock audits, redundant approvals, pick/pack/ship audits, cycle counting? Another example of overprocessing the the warehouse is the failure to rationalize the supply base and concentrate relationship management on a few top-tier suppliers. What about rationalizing the carriers? Both result in inefficient duplication of resources, decisions, and communications.
Moving Product - like overproduction, the unnecessary movement of product can occure both within the warehouse and throughout the entire supply chain. Too many steps, too many stops, unnecessary movement from suppliers though master DC’s to regional DC’s for further deployment to customers can be deadly drivers of cost and time, labor, and space.
Moving People - in the warehouse an enormous percentage of people’s time is devoted to movement, such as picking, put-away, and replenishment. If a facility isn’t well laidout with easy access to "A" items an enormous amount of time can be wasted in traveling empty. When good aren’t where they’re supposed to be the movement to the wrong location is both a defect and a waste of human motion.
Ineffective Inventory Control - creates waste a several levels. Excess inventory based on bad inventory data diverts limited capital into creation and maintenance of waste. Excess inventory results in consuming valuable storage space to hold unnecessary goods. A scarcity of items, on the other hand, results in stock outs, expediting, or lost orders.
50 things to do to free up warehouse space August 31, 2007
Posted by Lawrence Loucka in : Lean, Logistics, Supply Chain , add a comment
Business is growing and running out of space in the warehouse. What to do before moving to a new facility or pouring concrete? Fifty things to consider:
- Cross dock
- Narrow aisles
- Double deep racks
- Bridges over aisles, cross aisles, aisle ends, truck doors
- Re-slot forward pick locations
- Relocate slow movers and consolidate
- Change batteries rather than park and charge
- Pushback racks
- Pallet flow racks
- Carton flow racks
- Carousels horizontal or vertical
- Use uprights that only go to the top beam, close pack the top deck
- Shorter beams; 96" not 108"
- Triple wide beams
- Vary beam heights
- Double stack pallets
- Mobile shelving
- Purge excess, slow moving, obsolete
- Improve put away and pick cycle time and then cut safety stock
- Direct or Drop Ship
- Drop items from the catalog
- Put carton flow racks under pallet racks
- Put pick shelves and bins under pallet racks
- Slip sheets or low profile pallets
- Daily delivery of new pallets and packaging supplies
- Check out bound while picking or loading
- Check in bound while unloading or put away
- Store more than one item per shelf or pallet
- Consolidate partial pallets, cartons, bins
- Receive and ship on different shifts
- Redesign package
- Optimize pallet stacking pattern
- Select the right pallet
- Buy/Make to Order
- Buy in smaller lots
- Ship in smaller lots
- Receive and ship more often
- Make inbound receipt appointments
- Make delivery appointments
- Spot out bound trailers & load directly into trailer
- Eliminate inbound inspection
- Recalculate safety stock
- Recalculate order quantities
- Sell slow moving, return for credit, fire sale
- Donate, scrap, recycle obsolete
- Take assemblies apart and sell spare parts
- Combine parts in to kits
- Reduce the in and out queues
- Control SKU proliferation
- Pick directly into the shipping container
PowerPoint and other miscommunications August 5, 2007
Posted by Lawrence Loucka in : Consulting, Lean, Lean Sigma, Sigma , add a comment.gif)
Recently read Edward R. Tufte’s The Cognitive Style of PowerPoint: Pitching Out Corrupts Within and initially dismissed his thesis as troglodyte. Now sensitized, I’ve been watching for evidence of PowerPoint Abuse. Found an unfortunate example with two parallel teams during a strategic capital equipment review. Both teams were given the same mission and access to data: scrutinize the new capital equipment plans, challenge assumptions, collect new data and define cost reduction and risk mitigation plans. Both teams were staffed with bright industrial, process, manufacturing, quality engineers who pulled on other subject matter experts in their data gathering. Leadership effectively facilitated and guided both teams through the current state to future state diagnostic journey. Significant productivity, utilization, overall equipment effectiveness opportunities were identified and tested over the two week full-time exercise.
One team plastered their "war room" with all of their data, continuously rearranging their wall, retelling their story. The other team began typing their findings and abandoned their wall after a couple of days. Individual leaders would visit with the teams randomly throughout the study period but never "walked the wall", instead expected PowerPoint slides for the daily out briefs. Attempts were made to reconcile the two teams leading up to a joint presentation to senior management.
Bottom line - what’s the new equipment price tag to support the new 5 year strategic operating plan?
One team argued for showing both the prior and new estimates as side by side stacked bar charts, the other team just a table listing the $9.6 million delta.
Despite coaching challenges the delta display won out. Too bad because the Executive VP had remembered "the number" and misinterpreted the table. Had the first team taken the EVP on a tour of their wall the message would have been clearer.
Bow Wave July 29, 2007
Posted by Lawrence Loucka in : Definitions, Lean, Lean Sigma, Logistics, Supply Chain , add a comment
Keeping due dates straight in an MRP environment is a fundamental prerequisite. Plot a time series for the number of work orders, labor or machine hours, or dollars any you may find a significant amount of past due, due soon, and a short tail out into the future: you’ve got a demand bow wave.
John Scott Russell grew up in Glasgow where he was so fascinated by the great creak and roar of the first Newcomen steam engines at the Carntyne mines, that he abandoned his career in the church to become an engineer. In 1834 Russell accepted an invitation from the Union Canal Company to beat off the challenge from the new steam carriages and railways by designing better, faster canal boats. While testing his boats on the Union Canal near Edinburgh, he decided that it was the great bow wave the boats made that was slowing them down. As he rode along the canal in August 1834, he watched a rapidly drawn boat as it suddenly came to a halt in front of him. And something extraordinary happened: The great hump of water built up in front of the boat kept on moving as a single, huge wave, apparently without losing speed. Russell set off on horseback to follow this wave, and chased it for over a mile along the canal before it started to weaken.
Bow waves sap energy from the boat and reduce fuel economy; as well, large bow waves can damage shore facilities such as docks if a large boat sails past at high speed.
So too for a build up of work in front of an organization.
Reducing the size of the bow wave is a major goal of maritime architecture. Demand Smoothing, Master Scheduling, and Heijunka are supply chain tools for doing the same to manage the build up of work.