Process Improvement Team - Where to Start - Looking at Casting Inclusions

[achorste]

Good morning All (I always seem to come here for advice!)

I just started a new job a month ago with a new company (actually my last companies biggest rivals ), anyway, I've been asked to set up an improvement team looking at casting inclusions. The company I work for hasn't had much experience at all when it comes to formal problem solving and process improvement.

I've done my Green Belt and a few more projects & I've used a fair few of the other tools & techniques however I've never properly led a project myself (the green belt project were kinda hijacked by my old boss )

I guess what I'm asking is - where the hell do I start? I've got the team, I've got a meeting set up for Friday morning, however, how do I kick it off?

Many thanks for ANY help you could give,

Tony

[tony wardle]

Gee - sounds like the situation I am in at the moment. I must say, my solution is not to be found in any magical book or course, but it works for me.

Best advice that I can offer is :-
1. First understand the process - I usually get the team to tell me how it actually works (as opposed to how we hope it should work).
2. Write up the process as a flow diagram - making sure you have who does what, how. If there are measurements - put them in, making sure you know what course is followed if the measurement is out of spec.
3. Get the team together and start at 1. You find descrepancies. Get the true flow sorted.
4. With the flow diagram, you should have no open ended flows. If you do - this is part of the problem to be fixed.
5. Now that you have the blue print of what actually happens you can mark areas of comcern on your diagram and work on those.
6. Make one change at a time - get agreement from the team, and monitor the effect. The result must be measurable - saved time, money etc.

Improvement has 3 areas - where are we now, where do we want to be, how do we get there? Many people make the mistake of getting excited, determine where they want to be, but because they never found out where they started, they neve actually get to where they want to be. I have made this mistake many times - and it leads to alot of frustration!

Hope this helps?

[Geoff Withnell]

Originally Posted by achorste

Good morning All (I always seem to come here for advice!)

I just started a new job a month ago with a new company (actually my last companies biggest rivals ), anyway, I've been asked to set up an improvement team looking at casting inclusions. The company I work for hasn't had much experience at all when it comes to formal problem solving and process improvement.

I've done my Green Belt and a few more projects & I've used a fair few of the other tools & techniques however I've never properly led a project myself (the green belt project were kinda hijacked by my old boss )

I guess what I'm asking is - where the hell do I start? I've got the team, I've got a meeting set up for Friday morning, however, how do I kick it off?

Many thanks for ANY help you could give,

Tony

Tony,
The very first thing you need to do is establish your charter. It does not need to be a formal document, although I personally think that is best. But you do need to establish several things which will guide your team in its work:

1. What is your scope? You mention casting inclusions. Are you also going to work on voids? What about segregation? The scope not only tells what is your problem, it tells you what ISN'T your problem. This allows you to say "No" to someone who is trying to give you a bad case of "scope creep".

2. What is the business case for doing this work? What is is costing, in nonconformances, time, missed deliveries, or whatever. This lets you and your team know how important the work is, and how many resources and how much cash it is reasonable to expend fixing the problem.

3. Who is the process owner? When your team is done, who is going to be using your solutions on an ongoing basis? The process owner has to buy in to your solutions, or your project has no long term future.

Get your team's buy in on the charter, take it back to your champion/management and get their explicit approval. I emphasize explicit, because sadly, management has a tendency to "forget" that they have committed to support a team. Now you are ready to measure your current state, analyze the problems for root cause, develop ways to improve and implement controls to maintain the gains. Sound familiar?

Getting your scope and business case defined is usually a good kick off for a first meeting, since it gets everyone on the team on the same page.
Geoff Withnell

[antoine.dias]

On top of the previous posters:

- Get the team to search for causes of the inclusions.
- ( visualise the causes in an Ishikawa or fishbone diagram )
- Attack them one by one.
- Check the effectiveness of the actions taken.
- Look for further improvements.

Lots of success,

Antoine

[michellemmm]

Originally Posted by achorste

Good morning All (I always seem to come here for advice!)

I just started a new job a month ago with a new company (actually my last companies biggest rivals ), anyway, I've been asked to set up an improvement team looking at casting inclusions. The company I work for hasn't had much experience at all when it comes to formal problem solving and process improvement.

I've done my Green Belt and a few more projects & I've used a fair few of the other tools & techniques however I've never properly led a project myself (the green belt project were kinda hijacked by my old boss )

I guess what I'm asking is - where the hell do I start? I've got the team, I've got a meeting set up for Friday morning, however, how do I kick it off?

Many thanks for ANY help you could give,

Tony

Hi Tony,
It has been a loooooooooong time since I have worked in a foundry. Let me try to help.

You did not mention what type of casting or metal....Sand casting, permanent mold, investment, dry sand, green sand, etc....Are you involved in steel foundry?

My experience is in steel foundry....

The source of inclusion in steel casting can be attributed to design and process. Therefore, I strongly suggest to start PFMEA and DFMEA. Put a team together. You will be amazed to see how opinions differ without factual data.

Let me give you a quick start and talk about sand casting in steel foundry:
Inclusion in castings can be attributed by factors such as oxidation and sand and other processig material.

• Oxidation
  • Design of sprue causing whirlpool effect, introducing excessive oxygen.
  • Design of ladle. Bottom pour ladles are preferred. Teapot design is also good.
  • Pouring rate. Slow pouring introduces oxygen. I remember there was a rule of thumb that correlated the size of casting with pouring time and one was the square root of another. I cannot remember the exact formula. Fast pouring can also creates splash.
  • Size of ladle should be suitable for the operation/batch size and quantity. For example, if you have too many small molds, you need to optimize floor to floor time and pour as fast as possible with minimum number of ladles. Bad scheduling attributes to inclusion. You might want to design an experiment and optimize permutation and combination.
  • Large molds need to be poured first and then the small ones.
  • Ladle quality is very important. Sand and inclusion on the bottom of the ladles attribute to forign material inclusion.
  • Reusing ladles too many times introduces oxides. You need to find an optimum number suitable for your operation.
  • Lining too many ladles in advance is not a good idea.
  • Thermocouple cap can be reused two or three times. Controlling the number of usage is difficult. If the thermocouple cap is used too many times, it gives an inaccurate reading, hence slowing the pouring process.
  • The pouring rate is also related to defects such as pour short and cold weld.
  • Introduction of aluminum powder to the top of molten metal reduces the oxides. The amount should be calculated and monitored.
  • Consider performing DOE or correlation analysis between the metal chemistry, casting size, and other factors.
• Sand inclusion can be due to bad pattern design (gate/in gate, hot metal zone, abration, slow flow rate) or sand chemistry, or mold/core quality.
  • If you make you molds or cores days in advance and they absorb moisture from the humid environment, the chemical bond between sand grains starts to break down and when they hit molten metal, they get washed into the molten metal stream.
  • excessive temperature of molten metal can also break down the bond between the sand particles.
  • improper chemistry between the binders can create a weak bond.
  • sand size and geometry can also effect inclusion.
  • dirty pattern (cope and drag) make sand stick to the pattern and create weak bond for the sand. Patterns need to be sand blasted after so many molds or you pay for excessive cleaning operation and inclusion.
  • Improper handling of pallets and molds....When pallets are bumped together, sand chunks will fall into the cavity.
  • Excessive force in clamping can introduce micro fractures...
  • Consider setting up a factorial quality rating for core, mold, and casting quality.
  • Review the quality of the wash (protective coating) between cope and drag. If they are not dried up properly, you will have inclusion. If they are alcohol based, excessive alcohol will break down the bond between sand.

I hope this will give you a good start. If you need help, let me know.

[Caster]

Tony

Some more ideas (hard to beat michelmm)

Google is your friend, try an advanced search for pdfs. It will more likely return technical papers on your problem.

Look up the foundry associations, they all have numerous books and periodicals (http://www.afsinc.org/)

Call AFS, they have experts on hand to help

Involve your metal supplier, they may have experts

Look to local universities, some will have casting research facilities

Do you run the foundry, or buy from it? If they are the supplier, involve them.

Look to filter suppliers

In a word, look outside your team as well

I once solved a problem with much effort only to find it had been solved years before and was even pictured in a book I had on my shelf....d'oh!

[michellemmm]

Originally Posted by Caster

Google is your friend, try an advanced search for pdfs. It will more likely return technical papers on your problem.

Look up the foundry associations, they all have numerous books and periodicals (http://www.afsinc.org/)

Call AFS, they have experts on hand to help

Involve your metal supplier, they may have experts

Look to local universities, some will have casting research facilities

Do you run the foundry, or buy from it? If they are the supplier, involve them.

Look to filter suppliers

In a word, look outside your team as well

I once solved a problem with much effort only to find it had been solved years before and was even pictured in a book I had on my shelf....d'oh!

Thanks Caster for your post.

Inclusion is an the number one defect in any foundry operation. There are hundreds of sources. Starts from sales and ends at cleaning room. Everyone should get involved and know their role in defect reduction. That is why I suggested to start at FMEA.

There is one point I disagree with you and that is filtering suppliers. Years ago I resolved three critical issues with the help of my suppliers while I was working in a foundry. One of my suppliers was Ashland Chemical ( I don't even know if they still exist). Ashland Chemical used to provide free educational seminars. They knew more about our processes than us and we had a good technical department. The other supplier helped us to establish useful shelf life for adhesives that are used to attach the two half of the core and hence reduce the rate of inclusion. This supplier worked with me designing experiments for different application of wash; spray, mopping, and dipping with different chemistry and viscosities. I personally learned a lot from my suppliers. I even wrote a technical paper and was invited to present it in SME and SFS seminar. (years ago)

Regarding metal suppliers: Most of them are scarp metal dealers and I don't believe they can help much. The right chemistry is produced by combining the metals during the "heat" in furnace...

I strongly suggest contacting current suppliers and potential suppliers and establish a team to participate in inclusion reduction.

[achorste]

Well bugger me - I didn't expect this much help! Thank you everyone!

To answer a few questions:

It is investment casting (lost wax method) of Cobalt Chrome in small moulds.

The scope is looking at inclusions causing non-conforming parts after machining & polishing. Not a particular type of defect. Although I can already see this becoming too broad - I may well just concentrate on ceramic inclusions - supposedly the most prominent however I fear they may have been mis-diagnosed.

The foundry is in-house.

Thank you again for all your help!