Systems Theory and Evidence-Based Decision-Making as Keys for Arbitrating between Optimal Production and Efficient Maintenance: A Case Study

Dear Anouar Hallioui , Brahim Herrou, Ricardo Santos, Polinpapilinho Katina, Hassan Khadiri, and Ona Egbue

I have read your paper and my comments are:

1- It is difficult to read it because concepts are not explained

2- As far as I understand, the objective of your paper is to maximize profit, subject to two criteria, both asking to maximize productivity and at the same time to maximize maintenance efficiency, or minimize maintenance time.

You solve the problem in two stages:

First, a simple LP problem, determining the sizes of A and B, as well as the Z value of the objective function.

Second: You use a comparison between analytic and real values

3- In the Introduction, you say: “The opposition between maintenance and production is documented in the literature”, and I agree with this statement. It means that you want to maximize production, but at the same time you should minimize maintenance. Why do you consider both criteria for maximization?

4- You say: “In other words, that opposition is strongly justified by the silo mentality because of the bureaucracy and the reductionist management (or classical thinking-based management), which limits communication within a company and enhances barriers and ambiguity between its processes or services, including maintenance and production”

This paragraph is really difficult to understand. Why silo mentality is related with a fact, which is the existence of maintenance embedded in the production process? Look at my word ‘embedded ‘which means that both can’t be considered separately, as it could be in reductionistic management. As Moreno (2016) says ‘This largely leads to ignore how the relationships between the elements impact the whole system’

5- Your article is difficult to understand, because there are concepts that not explained. For instance:

· What is ‘handling and manufacturing chain’?

· Why is there a bottleneck and where?

· What are molds?

· What are groups? Are they two different devices?

· What are parts? Are they constituents of the devices?

· What are storage carts?

· What are ‘unplanned production time’? Is that equivalent to idle or no production’?

· Why carts must have the same number of devices each?

After reading your paper several times I reach the conclusion that your company manufactures two devices A and B, both in equal quantities but with different number of parts each. I guess that what you want to compare, is the total number of parts that can be optimally produced in 7.30 hours time and the total number of parts really produced.

If this is correct, it is a very interesting and rare problem because you can prove how close the analytical analysis using a MCDM method adjust to reality. This type of analysis is not common in MCDM because in general, we don’t know which the reality is, while it is known in your case. Really interesting, to check the validity of a MCDM method.

In page 5 you say “daily availability rate higher or equal to 97% and maintainability of 99% during the optimal planned pro[1]duction time are needed for the maximum productivity of the line”

What does it mean daily availability rate? Availability of what?

6- You say “The time necessary for manufacturing 1 group of parts of type A is 12 minutes and 40 seconds”

How can we use this information if we don’t now what a group is?

Does it mean that to fabricate all the parts of device A you need 12 minutes and 40 seconds?

Why maintenance is needed during the manufacturing process? Which is the reason of this interference?

7- In page 6 you say “(i) What are the quantities to be manufactured for the two types of plastic parts to maximize the productivity of the factory line and the profit given the maintenance function objectives and constraints?”

Types of plastic parts? Sorry, this is not understandable

8- I understand that your objective, with variables x1 and x2 is to maximize the number of parts that are in devices A and B ?

9- You say “(i) The time necessary for manufacturing each group of parts (type A and type B) is 12 minutes 40 seconds = 760 seconds.”

You lost me, because if each A and B devices have different number of parts, how can you produce them in the same time? It is reasonable to think that device A, with more parts, should take more time.

10- I think that the solution using the LP tableaux is clear an very understandable. I also solved the problem using the Solver in Excel and obtain the same results, that is x1 = x2 = 17, that is, we have to produce 17 devices of each type. Of course, I got the same result for Z. It appears that there is not an integer solution

11- The second part of your problem is to compare the production and idle values between the analytic result and reality. And this for me the most important part of your study, since it proves that using LP methodology reproduces quite effectively reality.

As I said, this is a very valuable problem that can help a lot of people. Unfortunately, in my opinion, it is not clearly written, worsened by the lack of explanation of terms.

I hope my comments help

Nolberto Munier