Venting - Root Cause + Team Work
I was in the middle of the critical stages of a big, big program.
A complex product with challenging geometry and tricky surface-finish requirements.
It had all the factors and engineering head-scratchers that every tooling engineer relishes.
Fifteen parts to be molded. More than half were cosmetic dependent.
The projected yearly and lifetime volumes were enormous.
more vendors means more fun
Big volumes. Yipeeee.
But you know what that means?
Yes. You got it.
We had to involve multiple vendors.
And more vendors means more fun. Right?
Gulp.
At the beginning of DVT we noticed that Vendor B was doing much, much better than Vendor A.
Hmmmmmmmm, I thought. That’s strange.
The tool design is the same, resins are the same, machines are similar.
Vendor A wasn’t reporting issues until last week.
What’s going on here?
There is something strange that we are missing.
Strange but interesting.
As a tooling engineer, I’m both concerned and excited. In equal measure.
time for a vendor visit
It was time for a vendor visit. Time to see the tools and put eyes on the molding process.
What are we missing?
This just doesn't add up.
Thursday Morning
Two days later, a groggy me woke up in a hotel room on a Thursday morning.
Today’s the day I get to go onsite at vendor A. I still have an equal mix of concern and excitement.
What’s causing these mysterious issues?
The van ride was two and a half hours from my hotel.
This gave me plenty of time to play mental troubleshooting games.
“I wonder what’s causing these mysterious issues at Vendor A?”
My mind starts to fill up with a shopping list of possibilities.
Material preparation
Incorrect resin
Machine issues
Tool construction
Correct molding process
Barrel and screw issues
So many potentials.
It could be any one of these. A combination of two or more.
Or something completely different.
Ok, I will save these considerations for now.
My brain is beginning to overheat.
For troubleshooting, I find it’s better to approach with an open and relaxed mind.
Look at things with fresh eyes. Try to park any preconceptions before entering the molding area.
I arrived at the vendor factory at 10.30am.
There was a big crowd gathered in the conference room. It was good seeing all the familiar faces again.
The atmosphere was a bit tense due to the mysterious molding issues.
An anxious and ready team with presentations and 6,478 slides investigating root-causes and possible next actions.
take a walk to see the tools running
“Let’s skip that. I would prefer to take a walk to see the tools running”.
We decided to head directly to the running of the main enclosure tool.
It was a two cavity tool on a 150T machine.
The tool looked good. The machine looked in great condition.
And the process was running smoothly.
Process parameters were in line with documented expectations.
Cycle time of fifty seven seconds.
So far so good.
Everything looks in order. Everything looks too good.
Can’t believe I get this positive impression and yet the molded parts have such serious cosmetic issues.
What are we missing here?
weird flow lines and some wavy sink
I’m feeling curious and excited.
This is the reason why I visited this vendor on that Thursday morning.
The parts have weird flow lines and some wavy sink patterns.
Let's check the machine in more detail.
Maybe there is something old, loose or broken that is a contributor.
The machine was two years old and in well maintained condition.
What about the barrel and screw?
A worn screw or a dodgy check ring can cause amazingly random issues.
The vendor changed out the barrel and screw when they started seeing these issues.
A fantastic variable elimination action. Kudos Vendor A. Well done.
However, it made zero difference to the molded part quality.
Oh boy. I was secretly hoping that the screw was a contributor.
walk through the material preparation
Ok. What's next?
How about we walk through the material preparation?
Where’s the material stored?
What’s the drying process?
How does the material get delivered to the machine hopper?
Any contamination risks in the process flow?
How is moisture managed and tested?
We took a walk over to the material warehouse.
Material bags were stored in a dry, tidy and well managed area.
Vendor was following the drying SOP we had asked for.
Testing frequency, testing equipment and testing documentation were all in order.
To be sure that everything was as it appeared; I asked that we do immediate MFI and moisture tests.
what are we missing?
I followed the full process from sample collection to results processing (moisture and MFI).
Everything looks good.
The vendor had professional operators and procedures. The team knew what they were doing and it was obvious that they have been doing this per SOP.
Great team. Great to see.
All look’s good.
But all’s not good.
What are we missing?
I’m getting a little nervous at this stage.
Thursday Evening
It’s now 6.00pm on Thursday evening. We decided to call it a day.
The vendor team is feeling the effects of a hectic few days. Time to get a bit of recovery.
Get some rest and think about what we can do for tomorrow.
Roll on Friday.
On the van ride back to the hotel, I called the tooling manager.
tool to be on a bench in the toolroom
“Hey William. The team is doing a great job. It’s obvious that you are professional and following best practices. Please forward my thanks for the top class effort.
Can you help arrange for the tool to be on a bench in the toolroom for tomorrow morning?
It’s difficult to see everything when the tool is in the machine.
That will help us all have a closer look at the tool construction.
We can look at the fitting and machining details in.
It may give us a few new clues.”
maybe we missed something
I got back to my hotel just after 8.00pm. Feeling groggy and still thinking about today’s actions.
Time for a quick bite before getting ready for sleep.
I was running today’s investigations through my head while waiting for my food order.
We checked a lot of stuff. Material preparation, machine function, molding parameters and material delivery. I was hoping that one of these would give us a clue where to focus next.
Maybe we missed something in what we reviewed.
But what?
What if tomorrow leads to a dead end?
Oh boy. Don't want to think of that.
Let’s be positive. It will all work out.
Just need to be patient and observant.
Time for some sleep.
Friday Morning
It’s now Friday and I am back at the vendor.
The tool is in the tool room as requested.
We ask the tool makers to split the tool and give us a call when it’s ready.
“Can you have it open on the bench in a few hours”.
We walked around to check the other tools and machines.
30% of the tools are ok as the parts are non-cosmetic.
The rest have strange cosmetic issues. Similar to the main tool but less severe.
We got the call at 1.30pm. The main tool is ready for inspection.
The team headed to the tool room. I was feeling a bit negative and concerned.
What can the root case be?
What if we don’t discover anything new today?
The tool was in two halves on the bench. The core side and cavity side awaiting curious eyes.
We had good lighting and the toolmaker crew were present and ready to get stuck into the discussion.
Perfect. All hands on deck. You couldn’t ask for more. A real, singular team feeling.
I’m getting a great impression of this vendor. We still have issues but their brand is well up in my opinion. You learn a lot about teams when trying to solve complex problems.
Let’s dig into the details here.
See what we can see.
The machining on the core and cavity looked good.
Did you ever notice that tooling engineers have a strange habit of touching steel edges and finishes? I guess there are eyes in the fingertips.
Before you ask. Yes. of course I had my hands scanning the steel.
I could tell that this tool got a lot of love from a professional team.
The ejection was well executed and fitted. Slides were constructed with smooth action and wear plates. Tool alignment controls were solid and large enough for the tool.
Chamfers and rads were done with care and pride.
This is a well built tool.
What are we missing?
Everything looks in order. My blood pressure is rising a bit.
The tools are not working well. There must be something else.
Note to self: Stay positive. Keep eyes and ears open.
Friday Afternoon
We decided to take a coffee/tea break and come back in an hour or two.
Sometimes it’s best to step away and hit the reset button. Think of something else for a few hours. It works for a cell phone so it should work for us humans.
When we got back to the tool room I decided to take a different approach.
I cleared my mind of all the technical tooling stuff. Decided to dump all the mental data from the last few days.
And asked myself “Is there anything that looks strange on the tool?“
Using my eyes only I scanned the tool while playing this question in my head.
I scanned. Asked the internal question.
“Is there anything that looks strange on the tool?“
And scanned again.
Question. Scan. Question. Scan.
I feel like I was in this mode for ten minutes.
And then something popped.
Oh. How did we not see this before?
There were various discolorations around the part cavity.
Dirty. Rusty looking. They looked like corrosion of some type.
Or maybe a burn mark.
But this was a new tool. Only running a few weeks.
Hmmmmmm . . . .
Could this be the clue we were looking for?
It may also be nothing. Let’s dig deeper.
I got the attention of the tool room manager.
Me: Hey, what’s your general strategy for tool venting?
Manager: Well, we add vents at the end of fill.
Me: What about other locations around the part?
Manager: Yes we do. Sometimes. But only if needed.
Me: Oh. Let’s chat more about venting.
I got the feeling that this vendor was a bit reluctant about adding venting.
A bit fearful, perhaps. I have seen this before.
Here’s a surprise for you. This attitude isn’t unusual in the molding industry.
Vendors are nervous adding venting for a few reasons
Flash
Customer upset
Cosmetic risk
These myths have continued to grow over many, many years.
There is a general misunderstanding of how vents work and the advantages they give.
Vendors are reluctant to add vents. And when they do . . . .they are usually too shallow.
Also, if you are the customer that doesn’t share the responsibility load with your vendor: you are contributing to this industry venting reluctance and fear.
Like most vendors, this team applied themselves with serious professionalism.
I always like coming to visit as they are a fun group to work with. We can have a few laughs even when things are a bit challenging. Sometimes, this is the time when a bit of light relief is needed.
It’s good for the team to be loose and flowing to be creative. Adding stress to an already difficult situation never helps. Be helpful. Manage the mood. Look after team members.
Friday Evening
Ok. We may have an opportunity here to improve things.
It’s obvious to me that the vendor needs a bit of help with venting.
And a bit of shared responsibility to reduce the burden of risk.
I'm beginning to get a bit too excited. This could be it! I pull myself back. Let’s play this out fully before getting over excited.
There is a positive chance to improve the tooling on this program.
And help the vendor improve their understanding and application of venting.
This is all good. Let’s go.
We strolled back to the conference room and I spent an hour with the team slowly explaining the basics of venting.
I started with the myth that too many vents are bad for cosmetics.
Broke down the conception that vents cause flash.
Explained how vents make filling smoother and easier.
Vents allow gas to escape and reduce the pressure in the cavity.
It generates extra opportunity to adjust and improve the filling process.
Simply put, it makes life easier for the material entering the mold.
Easier to fill means less forced packing. Less packing means less flash risk.
We talked about how venting during the fill takes the load off the final fill venting.
We discussed putting generous vents in the runner system. This will get rid of a lot of gas gunk before that material reaches the part cavity. This is a free advantage with zero risk.
Then we chatted with the team about vent depths and land width.
My dept suggestions got a few wide eyed expressions. Good. This will take a bit of work to convince change. And be a memorable discussion.
We went deeper (pun intended) based on their wide-eyed reaction. I asked for feedback on their thoughts.
We spent time feeling out their concerns and giving attention to their experience.
A great discussion. Open. Honest. Two way exchanges.
In the end we settled on a depth strategy. The biggest part of the persuasion was me sharing the responsibility for the feared outcomes. Sharing the load. Mental and physical.
Again, this strengthens the sense of being on the same team.
Note
Vent depths will depend on your resin.
Check these out. The data is readily available.
And be brave. Go to the higher end of the recommendation scale.
“Ok everyone. Let’s head to the whiteboard”.
The whole team, all stakeholders, joined the session.
We tried to make it as positive, interactive and fun as possible.
We sketched and documented vent locations, depth and atmospheric escape.
Capturing all the details discussed in the previous two hours.
We designed the runner venting. Locations, depth, land and escapes.
The toolmaker suggested adding venting to a few ejector pins.
Great idea. Let’s do that.
The tooling, PM and molding teams took all the information and went into a huddle for thirty minutes. They came back with a plan.
This work was going to take at least a day to complete.
It’s critical to get this right.
Venting is that important. Yes, it’s easy to apply to the tool. But it has a big impact on every molding process.
I listened to the feedback and communicated that I thought they may be squeezing the lead time a bit too much. The team were surprised to hear the customer asking to lengthen the lead time rather than force the time available. This was a first. You could sense the combination of relief and happy confusion.
We decided to take time to do this properly and run the tool when ready.
A day sounded a bit rushed to me.
We communicated the lead time plan to the full vendor team. Management and technicians.
The level of importance was enforced by agreeing to run the tool again on Monday afternoon.
That will give the toolmaking team the weekend and Monday morning to finish the venting features.
The lead time understanding added to the sense of teamwork. It strengthened our relationship.
I wanted an opportunity to check the work before it went into the machine again on Monday.
The team was happy with this suggestion.
Note:
Always check this type of work before the tool goes back into the machine. Why?
It's proactive quality control. It enhances the “we are all on the same team” feeling.
You shoulder a share of the responsibility. Go team.
Make it fun. You are all in it together. Be thankful for the work and effort of the team.
Be understanding when there are times where some extra work is required. That’s expected.
Isn’t that a bit of an overkill, I hear you ask?
It’s not overkill to advance check the work.
Putting a tool in a machine, having issues and then finding something obvious when the tool is taken down. This is not good. It wastes time. It frustrates team members.
Just know, there are usually a few small details that need discussion and possible improvement.
And that’s ok.
Friday Night
I was relaxed jumping back in the van on that Friday evening. Phew, that was a good day.
I was happy that we had discovered something positive that we could act on. A definite technical item that was missing in the tool.
Venting still had to be tested so I had to manage my expectations.
Is it the root cause of the cosmetic issues? Or are we still missing something?
Again, I opt to be positive. Plan for success. If venting doesn't work according to plan. Then we approach with a curious and open mindset. Continue good problem solving activity. Stay calm, Stay positive. Keep the team motivated and moving forward.
Monday Morning
On Monday morning we took a stroll down to the toolroom. The energy was more positive than last week. I could feel that the team was confident that these tool updates would make a positive difference. My personal feelings were not as positive. I needed evidence. (kept these thoughts to myself)
The team was working away. Venting work was 80% complete.
“Hey team. How’s it going? Anything you need help with?”
We took a look at the venting, and compared it to the plan we sketched on the white board on Friday evening. The positioning looks good. General widths look to plan.
The land looked a bit wide.
“Can we get a height gauge and a vernier over here please?
Let's check dimensions and depths.”
Land was 0.3mm wider than the specified 2mm.
The depth was a bit shy. I insisted, politely, on the exact recommended depth.
Vent depth is a key factor.
We also decided to add a few extra vent escape channels.
We leave the team to finish the work. And agree to have a final eyes-on when ready.
Two hours later we were all gathered around the tool like a swarm of flies.
The vents were now machined to the required depth. “Great, thanks for doing that.”
I noticed something else that needed a bit of attention. It was easy to see machining marks on the vent channels. Yes, these are tiny. Only visible at a specific angle. But this will affect the vent function and length of reliable function. It will cause restriction for the exhaust gas.
Note:
Vents need to have a polished finish. There should be no machining witness.
Also, the polishing has to be done in the direction that the exhaust gas will travel.
This will help reduce drag and restriction to a minimum.
Restate: polish in the gas travel direction.
We agree on an extra two hours to get the polishing done.
Monday Afternoon
Two hours to spare. What can we do to stay productive?
Let’s make a plan for all the other tools in the program.
We checked out the rest of the parts and formulated venting plans for each.
The main tool is on the machine three hours later.
It took another two hours to get the tool to running temperature.
The team dry-runned the system for twenty minutes. All was good. Let’s go.
You could feel the excitement. A strange combination of hope and expectation.
I was sweating a bit internally and externally. Fingers and toes crossed.
Monday Evening
Molding started up. We waited for the reliable parts to come out after fifteen shots.
The parts looked much, much better. To myself I was thinking “Oh, this might actually work.”
The illusive cosmetic issue had disappeared. The biggest challenge for the team was modifying the molding process. Why is this, you wonder?
It was much easier to fill the part. Parking was also lower pressure.
How can this be?
This seems to have fixed serious cosmetic issues and made the molding process easier. Win + Win.
The molding operator process adjusted and stabilized the process.
Another fifty shots were produced in order to be able to do a meaningful QC assessment.
The team was smiling and happy. Nice to see after days of problem solving pressure.
We went back to the conference room with the Tooling Manager, Molding Manager, PM and team lead.
“Let’s do a review of the last few days. What have we learnt?
But first. Please congratulate your whole team for the openness, design inputs and the high skill machining and finishing.
I appreciate the team atmosphere and the level of mutual trust. Great result due to a great team.”
We discussed the venting, the part quality and the modified molding process.
We decided to add an SOP follow up plan for future programs. We would revisit the DFM at T1 and input all venting details.
To add an extra layer of support and helpfulness, I agreed to supply a venting SOP and cheat sheet for the team.
Venting was updated on all the other tools.
Again, producing positive results on the cosmetic parts.
A fantastic result for all involved. You could feel the atmosphere change for the whole team.
The vendor was happy to have the program back on track. I was happy to have the extra backup of our second vendor. Win win.
The basics matter.
Venting is a basic that often does not get the attention it deserves.
Vendor History
I had the pleasure of working with Vendor A for another four and a half years. We made many, many complex parts and tools together.
We came up against sticky problems on several programs.
The difference is . . . We had a relationship. An understanding.
The vendor team was not distracted when I visited. I was part of their team. We had a relationship and a mutual respect.
It’s important to enjoy vendor visits. It needs to be enjoyable for both the customer and vendor.
The energy needs to be light and positive. You must melt away the “customer is a big deal” perspective. That only makes teams become unsure and afraid of saying the wrong thing.
It's give and take. Have fun in the process.
Takeaways
Add venting at T1, T2. The DFM needs to have a venting plan.
Keep an eye on exhaust patterns. Venting will need tuning for a few days/weeks.
Vent your runners. It's free. It works. Zero risk.
Go deep. Venting is usually applied to the lower side of depth recommendation. Be brave.
Polish polish polish. Vents need to look shiny and mirror like. And be polished in line of gas expulsion.
Check your venting every week. You will see gunk build up on the struggling vents.
Maintenance. Keep your vents clean. Venting care is crucial to continued function.