Posted on

As far as PAC is concerned, what is a constraint? Why is it important to be able to identify a constraint in the first place Answer

Types of Constraints

As far as PAC is concerned, what is a constraint? Why is it important to be able to identify a constraint in the first place?

 

The idea of bottlenecking can also be referred to as a constraint. It is important to identify a constraint because a company want to improve utilization of resources during production, reduce delay or down timing and to minimize excess costs. A company’s main goal is to produce efficiently and effectively without any constraints so identifying issues, fixing and maintaining control are all important steps that are vital to smoothing production. The book states that continuous improvement is an integral part of the theory of constraints philosophy which translates to; improvement starts and is guided by theory and constraints follow.

Jacobs, Berry, Whybark and Vollmann. Manufacturing Planning and Control for Supply Chain Management, 6th Edition. McGraw-Hill Learning Solutions, 2011.

What are the specific steps to managing constraints as outlined in the textbook and lecture?

Specific steps to manage constraints as per the lecture are:

  1. Identify the constrained resource.
  2. Decide how to make the bottleneck as efficient as possible.
  3. Make the exploitation of the constraint the top priority and all other decisions secondary.
  4. If more capacity is still needed, add capacity via capital investment, outsourcing, process redesigns, and the like.
  5. Return to Step 1 and find the next constraint.

So which of the five steps do you think is the most challenging when dealing with constraints; and why?

When looking at the steps on how to manage constraints I think the most challenging step is determining if more capacity is needed and how to add it. The lecture states that you can add capacity through capital investment, outsourcing and process redesigns which means that there are many options to explore before determining what you will use to add capacity. This seems as if it can create another time constraint on top of the one already present because of the fact that you have to look at the production process as a whole to determine what you can do. Time is everything in production and if company’s are spending too much time on trying to figure out how to fix or change a process and add capacity they can create unwanted costs.

 

 

Tthis step in TOC is critical because it requires a concerted effort to identify the true need for capital investments, process redesign, etc.

I think that deciding on how to make the bottleneck as efficient as possible is the more challenging one. Trying to figure out what is causing the bottleneck to make it more efficient can be difficult and time consuming. Say it is a particular job that someone is doing slowly because they did not have the right training or resources to do their job. It could be that the person just isn’t motivated either. When you are dealing with people it is difficult to find the right ways to improve the bottleneck as a person could one day do a job in half the time because they just felt like it. Depending on what the problem is also can be a costly measure to fix the problem as well. Say it is machinery that needs to be upgraded in order to be more efficient or another machine needs to be added to make it more efficient in order to keep up with demand.

To manage bottlenecking the company must follow the steps listed below:

– Identify the constraint

– Decide how to make the bottleneck as efficient as possible

– Make the elimination or management of the bottleneck the top priority and all others come second

– Add capital, outsourcing and process redesigns as needed to eliminate the bottleneck

– Return to the first step and manage to next constraint

I would say the most difficult would be deciding how to make the bottleneck efficient. Though most of the time there will be numerous ways to make the improvement, figuring out the best way is tricky. The ideal way would be to make the improvement internally without needing to add capital, man power or any cost to the company.   Making the bottleneck efficient requires a significant commitment from an organization; i.e., not to revert back to the “work arounds” if the results are not timely.

According to the text constraints are any resource whose capacity is equal to or less than the required demand is referred to as a bottleneck. As a consequence the fundamental principle of TOC systems is that only those work centers (or other types of resources) that are bottlenecks are of critical concern in scheduling. This is because the bottleneck work centers limit the overall production output of a plant.

Constraints are explicitly identified, and they’re buffered with inventory. Also, the constraint’s importance is made clear to the entire factory. Jobs are closely examined to find any that can be alternatively routed, even if the result is “excess cost” for the work so routed. The goal is always to break a constraint, or bottleneck condition, and thereafter identify the next constraint. Continuous improvement is an integral part of the theory of constraints philosophy. Moreover, the path for the improvement is directed by the theory, always following the constraints.

 

 

Which of the five steps do you think is the most challenging when dealing with constraints?

I believe the most challenging one out of the five steps when dealing with constraints is “exploiting the constraint”, the reason is because the activities of the chosen constraining element are examined , with special attention given to dedicating that element to maximum efficiency focused entirely on single primary function, to ensure that efforts relating to the constraint are on task and not wasted on any nonessential activity.

The textbook and lecture recommend that the approach to dealing with constraints is to utilizing Theory of Contraints (TOC) which is to improve the throughout the contraint or bottlenect. It also stated that utilizing of TOC follows a continuous improvement philosophy. That is when one contraint is broken, then next bottlenect is identified and then progross of breaking the constraint is restarted. The outline of the process are 1) identify the contrainted resource 2) decide how to make the bottle as efficient and all other decisions secondary 4) if more capacity is still needed, add capacity vis capital investiment, outsourcing, process redesigns, and the like and 5) return to step 1 and find the next contraint.

what else does the textbook say about constraints? Also, what are the specific steps to managing constraints as outlined in the textbook and lecture?

The text book states that we should follow the following 5 steps:

  1. Identify the constrainted resource.
  2. Decide how to make the bottleneck as efficient as possible.
  3. Make the exploitation of the constraint the top priority and all other decisions secondary.
  4. If more capacity is still needed, add capacity via capital investment, outstanding, process redesigns, and the like.
  5. Return to step 1 and find the next constraint.

How would you define the concept of Buffer Management in TOC?

The concept of Buffer Management in TOC is to provide timely protection of a production system from any likely or expected disruption. For instance, it provide the means by which the schedule is only as good as the ability to manage it or “make it happen”. This is where the Buffer Management (BM) control comes in and is a very important aspect of the TOC application.

Buffers are set into place for unseen variations in production, they are a proactive way to keep production in sync. There are 3 zones that help accomplish the management of buffers which are red, yellow and green. Red zone contains the orders that are scheduled next to the constraint and should rarely have missing orders. Yellow zone includes orders that are further out from the constraint and may have some missing orders. And finally the Green zone which also includes orders that are further out from the constraint but, will regularly have missing orders. It is important to have someone working on resolving the buffering issues so that production can flow smoother and on schedule. The larger the buffer size the more money that is invested and the greater chance of performance being effected.

Jacobs, Berry, Whybark and Vollmann. Manufacturing Planning and Control for Supply Chain Management, 6th Edition. McGraw-Hill Learning Solutions, 2011.

Buffers are put in place for unforseen variations in production at the nonconstraint work centers. The key to a successful implementation of TOC is the proactive management of the buffers. In many plants the management of the buffers is the responsibility of buffer coordinator. One way of accomplishing this is to divide the buffers in thirds. The first third is the red zone. The red zone includes the orders that are scheduled next on the constraint. The middle third is the yellow zone, and the final third is the green zone, which includes the orders that are the furthest out in the drum schedule. The red zone should rarely have missing orders. Orders that are missing from the red zone represent an immediate danger to the drum schedule. If an order is missing from the red zone, the buffer coordinator should be working nonstop on getting this order to the machine. If the red zone is always full, consideration should be given to reducing the buffer size. The larger the buffer size, the more money invested in WIP inventory. Therefore, buffers should be only large enough to ensure delivery performance to the drums. The yellow zone will occasionally have missing orders. The buffer coordinator should be actively working to get these orders to the buffer as quickly as possible. Likewise, the green zone will regularly have orders missing. The buffer coordinator should know where these orders are, and verify that they should arrive at the buffer shortly.

Reference:

Textbook

Some forms of buffer management can be use in term of physical stock and in term of time. Safety time can be preferable to safety stock for many businesses or companies with high demand and process variability. Hence, using buffers in time gives companies certain planning advantages. There are factors that should be taken into account during the determination of buffer. For instance, distribution of cycle times, learning effects, working hours, and outlier determination methods have substantial impacts on buffer calculations. I think one of the best place to have buffer management in place is before a bottleneck station.

Our textbook offered great insight for unforseen variations in a production at non constraint work center and also provide great technique that can be implement on a way of accomplishing flow of process in production environment.

 

in relation to our discussion on buffer management…, why would a company inflate the safety stock and/or safety lead time?

According to the text, while the entire buffer time is scheduled for every order, it is not expected that every order will arrive at the drum on time. Therefore, the key to a successful implementation of TOC is the proactive management of the buffers. In many plants the management of the buffers is the responsibility of a shop-floor scheduling person designated as the buffer coordinator.The buffer coordinator should know where orders are, and verify that they should arrive at the buffer shortly.

 

The Concept of Buffer Management in TOC, plays is an integral part of TOC execution. Whether the buffer being managed is the constraint buffer, the shipping buffer, or the assembly buffer, the approach is the same. Under Toc buffer management forms the basic for shop floor control.

Buffer management provides the means by which the schedule is managed on the shop floor. Buffer management is a process in which all expediting in a shop is motivated by what is scheduled to be in the buffers (constraint, shipping, and assembly buffers). Buffers can be maintained at the constraint, convergent points, divergent points, and shipping points. By expediting this material into the buffers, the system helps to avoid idleness at the constraint and missed customer due dates. Also, the causes of items missing from the buffer are identified, and the frequency of occurrences is used to prioritize improvement activities.

Can you provide an everyday example of buffers in action?

the book talks about safety stock and safety lead, both provide a cushion against variations in job flow. “Reducing the effect of uncertainty is also discussed which includes realistic schedules that meet material and capacity limitations, involving the appropriate level of work-in-process inventory, the capacity utilization attainable, degree of schedule protection, and batch size controls can all be applied to the TOC procedure. ”

Jacobs,R;2011(pg.286)

I think safety stock is a good idea for most companies,especially if you use a lot of small parts(washers,screws,etc.) when manufacturing. Being able to schedule lead time during your manufacturing schedule would help if you have a supplier that constantly delivers materials late.

Buffer management is controlling the bottleneck by way of buffering the next production process. Basically the idea is to build up enough product in order to compensate for the slowing in one production area. For example, if area A produces slower than area B, are B would not begin production until there is enough of A completed to not distrupt production flow of B once it has started.