Cellular Manufacturing versus Group Technology

Via Scoop.itCellular manufacturing

Arif Nurrahman’s article presents Cellular manufacturing (CM) as an application of Group Technology (GT). This is the view of GT experts like Burbidge in Production Flow Analysis, for example, but is at odds with the Lean approach, as explained, for example, in Sekine’s One-Piece Flow, or in Lean Assembly. Group Technology creates product families based on feature similarity, ignoring the demand structure.   The Lean approach is to make it easiest to do what you do most often and therefore starts by classifying products as Runners, Repeaters and Strangers based on demand. Runners are few in number but have a sustained demand high enough to justify dedicated lines. At the opposite end of the spectrum are the many Strangers with low, sporadic demand that you make in a job shop. In-between are the Repeaters, for which you use Group Technology to arrange into families for which you build flexible lines.
Via manufacturers.blognotions.com

5 comments on “Cellular Manufacturing versus Group Technology

  1. Pingback: Cellular Manufacturing versus Group Technology | Michel Baudin's ... | Cellular manufacturing | Scoop.it

  2. Dr. Gordon Knowles, in the IIE discussion group on LinkedIn, asked:

    Why versus?

    Jim Crockett elaborated as follows:

    I agree with Dr.Knowles. Exclusionary thinking is SO common as “either-or”. Group technology can usually be pooled within cellular manufacturing. Except for cellular manufacturing that can be accomplished by a single operator– I performed a GTT study for Yoder rolling mill output standards in the 1967 as a co-op student at a Tier I automotive manufacturer that took six weeks– it was still being used in 1977 when I returned as chief engineer and was not substantially changed until the late 1980’s. This lengthy relevance and accuracy of work study can happen when an operator performs all the maintenance, indirect labor, as well as the direct job elements in a continuous output situation with the only significant change element except for material and tooling changeovers and automation elements do not redefine a continuous flow process.
    Terminology? “Focused factory” and “factory within the factory” (1970 terminology) and finally “cellular manufacturing” (1990 terminology) became the new fad terminology of looking at job design organization, but utilizing the same logic.

    I used to buy Swedish – built Volvos in the 1980’s, since they primarily used “cellular manufacturing” (not then yet so named) that greatly increased quality, based on the ownership of the workers performing a variety of tasks to produce a final product instead of an intermediary one that did not produce ownership of task To me. “group technology” is slightly different in the way to focus optimization by manufacturing activity occurrance (and randomness) than the previous methodologies and is a little more easy to deal with the continously increasing stream of new technology of automation to those pool of tasks. Task design is becoming greatly more dynamic with the increasing stream velocity of new technology tools today for task definition and completion, so “group technology” will continue to foster more specialization within the work group and will probably displace other terminologies.

  3. Tony Mafera, in the IIE discussion group on LinkedIn, commented as follows:

    If the parts are grouped by product feature/geometry etc… why not have the designers make them the same? saves alot of resources!
    If you group by process method then you’re back to the old batch and move methods–aren’t you?
    Don’t get lost in the accounting belief that making more per unit of time is better–long live the GOAL!
    thus the point is modular design (group features into one design) and cellular manufacturing (1 pc flow) using equipment which provides the best quality with the lowest investment cost–usually the simplist Mfg method is the best so everyone understands!–Poke-Yoke is a must!

  4. Thomas J. Sowell, in the Lean & Kaizen discussion group on LinkedIn, commented as follows:

    I find that Group Technology is best suited for a family-of-parts, eg., parts that are similar in size, shape, materials, tooling and fixturing, set-up and cycle times, dimensional part configuration and other similar traits. Whereas Cellular Manufacturing strives to complete the manufacturing operations from start to finish in one work area, utilizing floor layout, manpower, and labor requirements, but not necessarily taking into account all of the above similarities.

    My response:
    Many Lean cells do not cover manufacturing operations from start to finish but only a segment of the process. This may be because some of the operations in the process are still performed on monuments that cannot be dedicated to the cell, or because the process is too long for a single cell.

    One of the key characteristics of the cell concept is the small team that operates it, and it cannot exceed 8 members for the positive group dynamics to occur. If your process requires 50 operators from start to finish, you cannot run it in a single cell.

    If you collocate all the resources needed for this process, you may have a focused factory, but not a cell.

  5. Pingback: Shortage of skills, not yet – but very soon – a wake up call (part 2) | Wiegand’s Watch | Michel Baudin's Blog

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