Taking time and cost out of work-in-process handling.
The barriers to efficient work-in-process operations are legion these days. Some of the more recognizable (and recurring) obstacles include: increasing volumes; smaller order quantities; more customization of products; shorter lead times; and greater cost pressures.
And when two or more of these occur simultaneously on the shop floor, watch out. They tend to pull in opposite directions, stretching shop floor resources dedicated to managing work-in-process.
Nevertheless, you carry on, often with heavy reliance on informal systems that were never part of the original materials handling and information system plan.
Your operations don't have to remain that way. Careful planning can modify your shop floor systems to accommodate your business as it now exists, not as it once was.
The first step in that process is to determine where systems now stand and what they need to become.
Consider the story of gaming machine maker IGT of Reno, Nev. Years of steady growth and expansion had resulted in 17 manufacturing locations. Even though the 17 were relatively close to each other, top management decided it was time to consolidate manufacturing in a single facility.
That decision opened the door to a rethinking of the production process. Managers started by focusing on ways to shrink production cycle times and cut costs by reducing inventory.
The result is a shop floor with a series of progressive assembly conveyors that accommodate production of any of IGT's gaming machines. In addition to that increase in flexibility, cycle times have been cut by a third.
In a vastly different industry from IGT is Signicast, a manufacturer of metal castings. After many years of operating as a traditional, batch-mode job shop, Signicast broke that mold and looked for an easier way to march everything through its process.
With the help of three automated storage and retrieval systems (AS/RS), several robots, and multiple conveyor lines, the company now practices continuous-flow manufacturing along a single spine. Handling costs have been cut 25% and production time trimmed 75%.
As Signicast, ITG and many other manufacturers have found, a broad-based plan for upgrading materials handling and information systems starts with goals.
The chart below will help you begin. By setting priorities and establishing improvement targets, you will be better able to plan systems that meet your specific needs. This information will then help to keep everyone on the same track.
With definable goals in mind, you are then ready to focus on three key aspects. These are:
* The physical movement of materials
* Production planning and scheduling, and
* Identification and tracking.
Probably the three characteristics most often planned into WIP handling systems today are flexibility, flexibility, and flexibility. The trick to good planning is determining the form and degree of flexibility that your WIP needs.
Several inputs need to be taken into consideration to arrive at a workable plan. These include: a profile of all raw materials, components, and assemblies; activity levels of these various types of WIP; a production profile for each major stock keeping unit; production estimates for the fore-castable future, and; expectations for changes in the current product line.
With this information, you will have a better gauge of the physical details and frequency of handling WIP for the near term and farther into the future.
An evaluation of the current materials handling system is also in order. Chart how WIP is being stored, retrieved, and routed throughout manufacturing.
In all likelihood, procedure manuals will give you one view of WIP handling. The people who work on the floor day in and day out will give you another. They will probably provide the best practical insights into critical practices such as materials management, parts sequencing and staging, and production/order priorities.
The ability of the system to deal with planned and unplanned events will also become apparent. This is when the informal systems created to cope with changing needs will become obvious.
Bottlenecks, duplicate handling, and the degree of practical integration between handling systems are three flash points to watch in particular at this stage.
The drawings on these pages detail four different schemes developed to maximize the flexibility of WIP handling. In each of these systems, flexibility was a priority but resulted in quite different solutions based on the work-in-process details of each facility.
In many operations, there is at least a partial disconnect between production plans/schedules and the coordinated movement of WIP on the shop floor.
A thorough review of operations will detail where the breakdowns occur. Solving them, however, will likely require more than just a good materials handling plan. This is where software comes into the picture.
Fortunately, there is now a type of software--manufacturing execution systems (MES)--that can bridge the gap between the intended schedule and what actually happens on the shop floor.
Planning and scheduling production is still the bailiwick of material requirements planning (MRP) and manufacturing resource planning (MRP II) software. But now MES uses planning and scheduling information as the basis for managing WIP and shop floor operations in real-time, dynamically compensating for obstacles as they occur.
In short, MES manages the efficient use of shop floor resources including materials, workstation and materials handling equipment, and labor.
Today, most MES packages do not control materials handling equipment. However, deliveries and transfers from storage and staging equipment can be managed with parallel control systems.
Yet another type of software, enterprise resource planning (ERP), is in the early stages of use to control manufacturing operations too. Traditionally related to financial and human resource functions, some ERP packages have the capability to tie together manufacturing functions such as bill-of-materials and shop floor scheduling.
A WIP identification and tracking system is the third component to consider when planning for improved shop floor operations.
If bar codes, radio frequency data communication (RFDC) terminals, or radio frequency identification (RFID) tags are not currently part of your operation, it is time to give them serious consideration.
Ever increasing numbers of manufacturers are employing these and other automatic data collection (ADC) technologies to identify WIP and attain inventory accuracies that exceed 99% in storage and staging areas. Just as important, the technologies track individual units of WIP moving through manufacturing.
The most comprehensive approach starts with identifying raw materials and components when they arrive in the facility. These systems then track assemblies as they pass from workstation to workstation and become finished goods.
Throughout the process, WIP location and status data can be made available to whatever control software manages the operation. The most integrated data management systems use this information to provide customer updates.
While there is no single answer to creating an efficient flow of WIP on the shop floor, there is no doubt that planning all key aspects up front is essential to success. Otherwise, you can plan on living with a system that looks different but doesn't deliver the goods.
Planning your WIP improvements Priority General Goals: High Low Boost productivity Integrate production stages Increase throughput Manufacture in smaller lots Reduce order turnaround time Improve quality Maximize flexibility Eliminate redundancies Accommodate more product variations Meet tighter schedules Target (% change or other measurement) Boost productivity Integrate production stages Increase throughput Manufacture in smaller lots Reduce order turnaround time Improve quality Maximize flexibility Eliminate redundancies Accommodate more product variations Meet tighter schedules Specific Goals: Priority High Low Shrink floor space dedicated to WIP storage Reduce WIP inventory levels Increase inventory accessibility Increase inventory accuracy reduce distance from storage to workstations Increase floor space dedicated to production Trim travel times between workstations Reduce distances between workstations Reduce number of times WIP is moved Reduce total manufacturing cycle time Target (% change or other measurement) Shrink floor space dedicated to WIP storage Reduce WIP inventory levels Increase inventory accessibility Increase inventory accuracy reduce distance from storage to workstations Increase floor space dedicated to production Trim travel times between workstations Reduce distances between workstations Reduce number of times WIP is moved Reduce total manufacturing cycle time
RELATED ARTICLE: What can you expect from MES?
* Manages resource availability including materials, production machines, and labor
* Prioritizes schedules and plans set by materials requirements planning (MRP) or manufacturing resource planning (MRPII)
* Controls flow of production units between machines
* Automates document control
* Provides quality, process, and maintenance management
* Manages labor resource allocation
* Reduces manufacturing cycle time
* Eliminates data entry time and errors
* Increases flexibility
* Boosts inventory accuracy
* Slashes work-in-process levels
* Trims lead times
* Improves product quality
* Reduces paperwork
* Empowers people on the shop floor
* Boosts customer service levels
RELATED ARTICLE: Two ways to manage WIP
Materials handling equipment can be integrated in a wide range of combinations to meet your WIP management goals and operational needs. Here are two approaches to handling WIP efficiently.
WIP never stops moving
Kits are built manually from inventory stored on shelves and racks. A roller conveyor delivers kits to an assembly conveyor spurs feeding multiple workstations. Finished assemblies are placed on that same conveyor and routed to a test station spur. Finished goods are staged on an accumulation conveyor.
Two identical handling systems manage parallel work flows
Both sides of the shop floor are identical, allowing WIP to move at two different paces as needed. Single girder top running cranes deliver early assemblies to jib cranes for further work. Double-girder cranes deliver finished assemblies to the end of each production line.
RELATED ARTICLE: Using AS/RS for multiple functions
In these two layouts, automated storage/retrieval systems (AS/RS) are used to stage WIP, store production tools, and organize finished goods.
Work buffers keep WIP close to workstations
Stored raw materials are delivered to workstations adjacent to one side of the raw materials AS/RS. That WIP (along with tools) is staged in the same AS/RS before delivery by an overhead power and free conveyor to workstations. The next step of WIP is staged in a second AS/RS that feeds final production. Finished goods are staged in a third AS/RS.
People touch parts only once in this system
An overhead crane moves steel coils from floor storage to the parts blanker as an AS/RS delivers the correct die to the blanker. A second AS/RS stages blanked parts that are carried by AGVs to stamping presses. Stamped parts are manually loaded onto a monorail for delivery to a third AS/RS. A second AGV system delivers parts on demand to the assembly line.
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|Title Annotation:||includes related articles on how to choose a manufacturing executive system and on using automated systems/retrieval systems|
|Publication:||Modern Materials Handling|
|Date:||Apr 15, 1997|
|Previous Article:||Make storage part of the flow process.|
|Next Article:||Orderpicking: the key to higher productivity.|