Airbag Problem

It looks like the recent recall of passenger side airbags is a result of possibly two causes.

It is a little difficult piecing together all the information.  And much of the detail is not even released.

Takata stated that the recent airbag problem is caused by:
1) excess humidity was allowed into the propellant wafers.  I am not sure if this occurred during manufacture or in the warehouse.
2) less dense propellant wafers.  I am not sure if the low density is only caused by poor machine capability, but now Takata states that there was an auto reject AR that was able to detect poor compaction, and therefore low density, but the AR could be turned off by the operator.

The result of both problems is that the when the airbag is triggered the propellant can burn too fast.  If the burn is too fast, the pressure gets too high too fast.  And if the pressure is too high then pieces of the airbag assembly can blow off.  Here is Takata's letter to NHTSA.

This passenger side airbag problem occurs with propellant wafers made from around April 2000 to October 2002.

The odd thing is, if you look at prior recalls of driver side airbags from Takata, they include propellant wafers  from round the same time and for the same reasons.  I am still linking it all together.

The lessons so far:

1. Track your material.  In the case of Honda, the location of specific lots of wafers could not be tracked which caused wider ranging searches.  In another specific additional recall, Honda lost track of a few thousand service parts resulting in recall notices being sent to hundreds of thousands of customers for serial number inspections of previously repaired cars.
2. Do a good investigation of problems.  When the 1st incident occurred there should have been an effective problem solving exercise.  However, it seems that there were some gaps in the process. As a result the recalls were slow to occur and covered too few suspect vehicles. This resulted in higher costs and risk to customers.  Did I mention at least one person died from this issue?
3. If a failure occurs on part A due to a component X, and a very similar component Y exists on part B, shouldn't component Y be examined to confirm whether both parts A and B need to be contained?  In fact in this case I am not sure how different the wafers are between driver and passenger side.  They may be common.
4. One of the problems noted is that an Automatic Rejection system was turned off by the operator.  Wow, so many issues here.  For the PFMEA team, now we have to be sure that expected controls are now locked out and will actually be functioning.  For the manufacturing team, they have to be involved in the PFMEA and know why the process is as it is, what the risks are, and have effective training. For the management team, what was the reason the AR was shut off?  Too high pressure for every piece of production? Why couldn't the people on the floor get the problem fixed? I doubt they simply opted to shut off the AR without some other frustrated efforts.
5. Also, the AR was not part of the propellant wafer manufacturing system originally.  But, it was added sometime in Sept 2001. Reject control is a common fight we have.  THe reject system has to be well designed and maintained.

PFMEA for Receiving Inspection

One of the rules of PFMEA is that an operation should consider the incoming component as good. A way to handle potential defective incoming material is to use the "receiving inspection" operation for the purpose of screening for failure modes and defects that can affect subsequent operations. The receiving inspection operation is already included in most PFMEAs. Sadly, the opportunity is almost always squandered.

Typically the entries are:

Potential Failure Mode (PFM): 

• Part damaged in shipping,
• Damaged packaging
• Dirty
• Defective

Be Specific About Failure Modes of Concern

Failure modes such as "dirty" and "defective" are too general to be useful. Sometimes you do find more specific PFMs:

• Part length too long or too short.
• Out of round

This is more specific, but focused on specific defects and not on potential failure modes.  More can be done to use the PFMEA beneficially to improve receiving inspection..

Include Failure Modes of High Risk to Your Operation

Why not use receiving inspection to actively question incoming material for ways it may affect subsequent operations? Try to use your Process Flow Diagram and PFMEA development to populate the receiving inspection operation with specific defects that can be a concern to your plant.

For example, consider an incoming die casting with sealing surface that your plant assembles with a seal. In terms of PFMEA you might include:

• PFM: Sealing surface does not seal
• Potential Effects of Failures (PEF): Leak fail at leak test
• Potential Cause or Mechanism of Failure (PCMF):
• Seal groove too rough
• Seal groove depth too deep or too shallow
• Sharp edge or missing chamfer

Using the PFMEA to focus in on areas of concern, like leak test failures, could help you populate receiving inspection with thing to spot check. In this case you might want to have receiving inspection spot check the sealing surface for roughness, grove depth, and sharp edges.
Another source of ideas are past supplier defect report (or 8Ds, or PRR, etc).

Include Failure Modes of High Risk to Your Customer

Another type of PFM that can be included in the receiving inspection operation are those related to component features that are not processed, used, or tested inside your plant. You might call these features "customer features" or "pass through features". An example of a customer feature might be a tapped hole on a machined housing that your plant assembles into a compressor.  Your plant does not assemble a bolt into the hole, your customer does.  If that tapped hole is defective for some reason, then your plant is responsible.  You can roll back the pain to your housing supplier eventually. But, everyone loses. You do the PFMEA exercise for these items in your receiving inspection section:

• Potential Failure Mode (PFM): Customer could not drive their bolt
• Potential Effects of Failures (PEF): Rejects at customer, containment, scrap costs
• Potential Cause or Mechanism of Failure (PCMF):
• Tap wrong size
• Tap too shallow
• Debris in tapped hole

Your controls section could include:

• Run a thread gauge for tap size
• Also check tap depth.
• Spot check for machining debris or swarf or turnings, etc

Example:

Take a simple example of an incoming wooden handle for a hammer.

Some typical incorrect Potential Failure Mode (PFMs) might be:

• Wood is dirty
• Wood is scratched
• Wood is wet

Some typical Potential Effects of Failures (PEF):

• Rejected hammer
• Bad handle attachment

A typical PCMF: 

• Bad receiving inspection

These PFMs are pretty much what you would come up with from the top of your head. There is no real additional value in listing them out. But what if we consider how the incoming material could lead to a failed operation? This is a situation where it makes sense to switch from specific defects to general PFMs. We want to use the PFMEA process to probe for new PFMs and PCMFs (in the case of receiving inspection, these will be incoming defects) that could nip us in the butt.


Here are a few examples of how this might work:

• PFM: Wood has some defect that prevents varnish adhesion
• PEF: If varnish does not adhere to handle it will flake off in the field
• PCMF: (need to consider defects that would cause poor adhesion of varnish)
• Wet wood? 
• Oily wood? 
• Rough texture?

Controls (detection) might be:

• Visual inspection for wet or oily wood.  No! typical and useless.
• You could do a humidity test with a sensor. (for water) 
• Maybe do a water bead test. (for oily)

Detection vs Prevention

By now you may be asking, why are we laying all of this work on receiving inspection?

True, what we have laid out are all detection type controls.  You really want to focus on prevention controls.

You can consider that we may be robust during launch with heavy receiving inspection activity.  And, leading up to launch the specific defects should be driven back to purchasing and supplier quality to confirm the suppliers have these defects in their PFMEA failure mode sections with good controls.

Over time the receiving inspection activity can be reduced based on data.

To reduce the burden on receiving inspection some of the defects could potentially built into your own process:

 As a poke yoke to detect incoming defects. Example, a pin to detect a machined hole.

 As potential failure modes in our own plant in operations that might can CAUSE the defect.  Example, damaging the tapped hole in your plant with an alignment pin or fixture. Or with a varnish or coating operation.

Summary:

• Be Specific About Failure Modes of Concern
• Include Failure Modes of High Risk to Your Operation
• Include Failure Modes of High Risk to Your Customer
• Continually Drive for Prevention at Your Supplier.

Battery Problems on the 787 Dreamliner

Battery incidents  occurred on 2 of 50 operational 787 Dreamliners.  One battery smoked while the 787 was in flight, causing the need for an emergency landing.   The second battery actually ignited while the 787 was parked on the ground.

Today Boeing announced that they have FAA approval for a list of design changes that they say should allow the Dreamliners to fly again.

The thing that struck me about the information is that the design changes all seem to address the symptoms of the batteries overheating.  They do not seem to address the reason, or root cause, of the overheating.

The last press release on the Boeing website is dated Feb 7 2013 and states:

"...the NTSB has identified the origin of the event as having been within the battery. The findings discussed today demonstrated a narrowing of the focus of the investigation to short circuiting observed in the battery
..."

The design changes reported by the New York Times Include:

• fiberglass-like insulation between the battery cells [whatever fiberglass-like means.  these sheets can supposedly "keep" a short-circuit (and the heat) from cascading to neighboring cells]
• stainless steel battery case instead of aluminium [withstands overheating battery heat better]
• titanium tubes to help vent smoke to outside the plane [yikes]

The only hint in the article at the search for a root cause is that the National Transportation Safety Board has found that in the Boston episode, a short circuit in one cell caused the battery to overheat and burst into flame on Jan. 7. 

But investigators in Japan have raised the possibility that a battery on another 787 nine days later started smoldering because it might have been hit by a surge of electrical current from another part of the plane.

A few things come to mind.

• The battery design engineers apparently did not consider the possibility of either 1) short circuit in a cell or 2) electical surge to the battery.  Here I think the DFMEA would have been the key tool from our toolbox.
• I can imagine the battery design team(engineers, purchasing, fabrication, etc.) busting their asses coming up with these fixes and thinking "figure out why the cell short circuited!" and "prevent the power surge from reaching the battery!" Was the short circuit caused by a design flaw, or a quality problem?
• When I hear "lithium-ion battery" I think of the many times I also heard "overheated". Remember the laptop that caused the pickup truck to burn up?  Remember the news about cheap lithium-ion nonbrand mobile phone batteries?  Come on!  Shouldn't the overheating concern been HUGE when doing the design and manufacturing development?
• I wonder if there was ever a case of battery or cell short circuiting in development or validation testing.

 

 

When discussing reshoring of manufacturing the focus is often on the cost/benefit anaylsis. 

Things like currency exchange rates, labor costs, productivity factor into the math. A more subjective discussion that sometimes occurs is whether we should reshore. Does it makes sense for a country to help nurture manufacturing within the borders. The article I posted about yesterday made the case that the US government "should shamelessly court companies to America and help them expand when they get here"

But what happens when other countries engage in such active incentivizing? The solar industry is in the news a lot because it is a new industry going through growing pains. The US, at local and national levels, did encourage solar companies to establish manufacturing sites with hopes that there would be new successful businesses established with new jobs and increased tax base. An Arizona plant is closing reportedly as a result of "part of solar trade battle between the U.S. and China".

I could not understand the direct relationship between the tariff war and the plant closing. Perhaps the plant imported components subject to the tariff from China that were assembled in the plant.

A commenter had an interesting take on the issue

Commenter:

I'm extremely sorry for the loss of jobs... but here's a different school of thought... if we *didn't* have the tariffs on Chinese imports, would we save 40% on solar panels and have more installations of solar, which would create tens of thousands of jobs here in Arizona.... plus the installation of solar panels on homes would result in low - or no - cost for electricity each month. That savings of money would then stay in the pocket of the resident, which would then hopefully go into the local economy. Savings like this could also be applied to people who replace their home internet, home phone, and home television services with the connection they get through their mobile phone... which in the next few years will be free as ad/app/etc revenue per device will exceed the monthly cost for phone service. If you're saying "no way", just remember when that thing called the radio and television came out.... people said no way will this take off, no way will you be able to get this in people's homes, and no way will you be able to make money off of it.

　

I think that in addition to the positive impacts he mentioned, the jobs, at least at this plant, would have been saved.  Essentially the Chinese government is subsidizing the US.

US Manufacturing Resurgence

The data for the amount of manufacturing occurring with the US continues to improve. Craig Barner at Forbes had a good recent status check.

Last August, Farok J. Contractor (professor of management and global business with Rutgers Business School) published an article: 7 Reasons to Expect US Manufacturing Resurgence. I loved this article. Contractor laid out a map of some of the factors that are driving some improvements in the level of manufacturing being done onshore. His list is comprised of a range of items from declining real wages and higher logistics costs. It is an excellent article. Contractor ends his article with some countering factors that would tend to drive manufacturing away.

Of course, all indicators are not positive. Three factors could inhibit the US resurgence: 

• The culture devalues science or engineering education. “Nerds,” “geeks” or “wonks” are at the bottom of the social totem pole compared to sports, film and media celebrities. A culture that emphasizes quick results and instant gratification deters students from tackling math, engineering and other challenging subjects.
• Too many students pursue a general college degree. According to a survey released by the Manpower Group in May 2012, talent shortages persist in skilled trades, engineers and IT staff, with “nearly half of U.S. employers struggling to fill mission-critical positions.” In OECD countries an average 23 percent of college degrees are in engineering, science or mathematics. But in the US such degrees comprise only 15 percent – and of these, foreign students earn a quarter of the degrees at the undergraduate level and some two-thirds at the doctoral level.
• US companies lack an apprenticeship system. In other OECD nations like Germany, alternative paths in education lead to diplomas or certificates in technical areas, with employees trained by the company in a particular technology and then retained in well-paying careers. Some US companies are trying this approach, highlighted by G. Bussey in an April Wall Street Journal article. For example, General Electric is sending new employees for crash courses in hands-on manufacturing or sponsoring two-week summer camps at universities on lean manufacturing for high-school students.

To all the manufacturing and quality professionals, you have a growth opportunity we did not expect to see back in ...say 2009. Now is the time to take your courses, get your certifications.

PFMEA Malaise

Time for an annual rant about the lack of PFMEA utilization within our manufacturing plants. It is 2013 people! How many more times will we ship a part "missing a hole"? Yes, the PFMEA form and process can be tedious. The risk ranking values can become a heated and lengthy topic themselves. However, the essence of the PFMEA, the search for potential defects and potential causes, is readily available. Unfortunately, still now as it has been through my quality history since around 1996, most PFMEAs are boilerplate written by one person. Hasn't the pain been enough? Can't we all get along? Get the team together. Stand at the process. Brainstorm. Could the process be skipped? Can the part go into the fixture upside down? Can the insertion be misaligned? on and on. Capture what you talked about and come up with prevention and control idea. Does anyone have a good example of how a team does an effective PFMEA? I would like to hear about it.