Sunday, March 20, 2011

Debate About JMP Minitab or Cornerstone

"Cornerstone is not user friendly; we need better data analysis software like JMP or Minitab for our data analysis."

Somebody brought up the topic in the last management review, and we spend sometime to debate the disadvantage of existing data analysis software and how it make our life inefficient.

I try not to involve in the discussion, because I m new to the software and basically not qualify to comment.

I use Minitab most of the time for data analysis, I got no experience with JMP and recently I try to play around with Cornerstone due to the need for Green Belt training. Honestly, I do face some problem at the beginning, mainly due to the arrangement of pull menu (the way Cornerstone group the data analysis function) and the reporting format. Technically, I don’t face much problem after hours of trial.

I didn’t spend much time to study the full function of Cornerstone, but at least, I get what I want. This is most important.

Personally, type of data analysis software to use is not the top priority, what is most important is the knowledge of data analysis, knowledge of digesting information from a given data set. Without the basic understanding, even given with the best statistical software, so what….

Data analysis software is just a big calculator for you to perform more complicated mathematic calculation other than the common Microsoft Excel. Whether it is Cornerstone, Minitab or JMP, bottom line, it must return the same result.

Saturday, March 5, 2011

Kanban Size Estimation

Is there a formula for Kanban size calculation?
Answer is : “Yes”. But the formula I ever learnt, I feel most of them are very academic and not really practical to the real production environment.

In my previous experience in box build assembly line design, I always consider a Kanban size = 3 into my production system. You may ask why 3, not other lucky number such as 8.

The secret behind is very simple, because my boss say : Kanban size = 3
He demand for 3 is based on his many experience in this field, 3 is the number where he think reasonable and achievable.

Anyway, you can’t just copy the number blindly and apply it to your production system. I’m sure it will not work. You have to go back to your production line, understand how the people run the line then only you can tailor a Kanban size the suite to your production system.

Hahha… talk so much, sound like all nonsense isn’t it.

Ok, lets discuss the case below.




Any Kanban size determination require basic process info as below
  • Takt Time and Raw Process Time (RPT) of your downstream process
  • RPT and Setup Time of your upstream process

There are two WIP Level that need to take care in a Kanban
  • WIP Level in Normal production run
  • WIP Level for “Pull” signal triggering

WIP Level for “Pull” signal triggering is the minimum WIP that enough to keep the downstream process running while waiting for 1st Lot replenishment from the Upstream process. WIP Level above this would be the WIP Level in Normal production run, where we can decide the level based on several considerations, such as

Optimum production time of Upstream process for every conversion
Production storage capacity
Resource availability to handle too many conversion frequencies

For this case, I would determine the “Pull” triggering point as below

Lot # = [(Upstream RPT + Upstream Setup Time) / Downstream RPT] + 1
So, answer is ~3 + 1 = 4

This mean, when the WIP level drop to 4 Lot, a signal will send to Upstream process for Kanban replenishment. But due to long set up time, Upstream process require 130min set up + 40 min production time to deliver the 1Lot to the Kanban tray. Per the RPT given, Downstream process require minimum 3Lot of material in order to keep the line running. I add additional lot in this calculation, because with the consideration Upstream process is not necessary handle one product, as conversion take place. Therefore, additional waiting time may be needed for last Lot clearance before machine conversion work can be start.

For the next level of WIP that supporting normal production run, you need to consider the most economy way to run the process on each conversion. There are company actually set the policy to limit conversion frequency ( such as 2 per day, 4x per day ) with the consideration of conversion cost, productivity and resource availability.

Just my Six Sense

Wednesday, March 2, 2011

Common Question In Six Sigma Training

In a Green Belt training, there are participant ask such question;

  1. This is a Lean topic; can it be a Six Sigma project?
  2. Can I do a Six Sigma project without using statistical tool?
To answer the first question, per my opinion, in fact, there is no such thing of Six Sigma project or non Six Sigma project. Six Sigma; by itself is just a systematic problem solving methodology that following the DMAIC flow. As long as you are able to define your problem statement, you are able to define a metric to measure your performance, high chance; you are able to solve your problem through the DMAIC flow.

For the next question, can we run Six Sigma project without using statistical tool?

Before giving a “Yes” or “No” answer, I think we have to make ourselves clear the statistical role in the process of problem solving. In any case, we use number for performance measure, to tell the difference of before and after a chance being introduced. Besides using number, I don’t see any method that can be precisely describe a chance.

Now, let me answer the question.

Answer to you is “Yes”, you can avoid using statistic in your Six Sigma project, if you are able to describe a change precisely or effectively to your boss and your boss accept your description, then, I don’t see any problem to apply your method in your Six Sigma project. This is the basic requirement you have fulfill in your Six Sigma project.

There are many tools in the Six Sigma program; there is no one solution that fit all. You have to apply your expertise, your experience and yours intelligent to pick up the right tool to solve problem throughout the DMAIC phase.

Hope I answer your question;

All the best to you