Repetition and specialization.

Instead of having a team of 20 dudes building a plane from start to finish, two guys will rapidly and previcely do the first approximately ten percent, then another team will do a little work, then another team, and another, and another, with each team specializing in getting really really good at only the part of the process they're involved in

I am in the automation business. The assembly lines are automated to create each item repetitively and within very tight tolerances. Its actually rare that items (here in the US) are 'hand built'. The machines are intelligent enough to reject any part during any process so that the bad parts/assemblies don't make it to market. An assembly line can assemble a V8 engine every 70 seconds with less then 10 people on that line.

[deleted]

That’s interesting thank you, but what happens to the rejected parts? Does it get recycled?

Must’ve take a lot skill to do things correctl, but what happens to the workers that get it wrong?

It all depends on the part and why it was rejected....some simply get rejected and scrapped, where others can be fixed and reintroduced on the line. Each station on the line keeps track of EACH part in the progression and can again reject the part (or assembly) at any given time. It can never be forced through production.

Now that we have global suppliers, each and every part is barcoded so if a part/assembly in Mexico get rejected that is intended for another assembly in the US then production might be halted until the process is fixed. All the lines are managed by a central database and can track quality in real time. This data then is incorporated in the warranty department so if there are a lot of warranty issues coming in once the vehicles are on the road we can literally track WHY it failed and then work to fix those issues. To prove this, you may get a recall on a vehicle and in that notice it will say 'recall for vehicles built during X time'....your recall will fix the problem they already found and fixed/updated in the assembly line

Well, they don't. They have tolerances. They can spend more time and use tools that were made more carefully to get tighter tolerances.

Every zero added to your tolerances adds a zero to your price, though. A huge part of the engineering process is to figure out just how sloppy they can get away with being.

They get fired, face a civil lawsuit at the absolute worst.

Only if you want your company to fail horribly.

If the process doesn't work right, you fix the process. Someone figures out what went wrong, and they figure out a better way of doing the task, and then that specific problem doesn't happen any more.

Firing people for making mistakes is an effective way to get people to hide mistakes, push blame on others, and otherwise make problems much worse.

There's a management joke: A worker who just caused a million-dollar failure is called into the manager's office. Worker says, "Well, I guess you're going to fire me." Manager laughs and says, "Fire you? We just spent a million dollars training you!"

Why do you think it's difficult to make them all nearly identical?

In an automated production line, it's easier to make 100 pieces that are almost identical than 100 pieces that are all visibly different.

Everything is made by machines.

A machine is doing the same motions and using the same tools each time, so the end result is pretty much the same every time.

Quality control. Each component is made to specifications, and if it doesn't meet specification, it gets tossed/recycled.

For example, car needs a 50.00mm +/- 0.01mm rod in length, 10.00 +/- 0.01 mm in diameter. Worker makes 10 rods. Quality control checks them, finds that one rod is 50.05 mm long when max permissible is 50.01. Tosses it.

They don't. They're all slightly different, but mostly the same.

They specify that the components be made within a certain tolerance for dimensions and other properties. They are designed that as long as the parts are within those tolerance the composite machine will work as intended. You can replace any part with another part that meets the original specifications and it'll work.

Thats a large chunk of my job.
I'm a process improvement specialist.

​

My role is to observe existing processes for loopholes and bottlenecks, and identify areas of improvement.
I think create the solutions, or a new process entirely and train the teams on how to use it.

Many companies don't invest in Process optimization, though they should.
You'll be amazed at how clunky the resources allocation process is, and how much it costs the company in tech debt and money.

My main goal is make a process as efficient as possible, so that in the long run, it will save the company time and money.

> You'll be amazed at how clunky the resources allocation process is, and how much it costs the company in tech debt and money.

"I just want to serve 5TB of data. Why is this so hard?"

Better way can also include stuff like https://en.wikipedia.org/wiki/Poka-yoke to make it more resistant to human errors.

Like if you have part A1, A2, and A3 that all can go into square hole B, but you actually want them to go through corresponding holes B, C, and D, then you could make it so it is physically impossible to put them all through the square hole.

An everyday example would be electrical connectors with different sized blades, or that can only be connected in a certain orientation because they aren't symmetrical.

We live near the Intel fabrication plant. They have a thing called "The Million Dollar Mistake" where a fab tech will drop the freshly cured silicon sheet for making microchips. Its about a million dollars worth of potential product and EVERY EMPLOYEE has dropped it at some point.

Tools wear. Every part is going to be a little different. Materials also aren't perfect. Even with lots of quality control 1 heat treat lot might be a little different than another. The grain structure of materials are going to vary slightly. Etc, etc.

One formulation of Murphy's Law: "If there's more than one way to do a task, and one of those ways will lead to disaster, someone will do it that way."

Running this backwards: If you don't want someone to cause a disaster, you make it impossible to do the task that way.

We do metal machining for the auto parts we make. The parts we make get randomly checked a couple of times per shift for all of the necessary specifications down to a couple hundredths of a millimeter variance.

If a part checks out of spec, the production of those parts are shut down and an engineer comes out to do what is necessary to make good parts again.

While they are doing that, quality control goes to the parts that were made by the out of spec machine and checks them, from oldest produced since the last line check, to the newest produced, until they find where the bad parts started getting made. They are then quarantined and sorted and measured, throwing out all out of spec parts.

They are all virtually identically, only having slight differences of no more than 0.02mm

Like others have said, they are not identical, but have tolerance requirements that must be met. I work in the aviation field and a lot of our tolerances are measured in increments of one ten thousandth of an inch.

That sheet is called “wafer”, cut from a monosilicon ingot, costs maybe 10-20 bucks. Ok, more if it was processed, but come on! It is like saying you are a mass murderer if you jerk off.

That's all well and good when you're manufacturing consumer goods

I'm specifically talking about aircraft manufacturing. Someone fucks up, people die. Investigations happen. Fingers are pointed. Someone gets fired, minimum.

Which is why I said "nearly identical", not "identical".

Tools wear, but to the naked eye that's not visible. There's also quality control and preventitive maintenance systems in place to make sure that tools don't wear out to the point where they start producing non-functional parts.

What ive seem, depends on the line, and what item.

Some or most items could de-route to a QA, Repair, check-up station that has manual controls to see if its still withing the standards to be still OK even if robots, cameras and what not said it was not, and on other places, they just plain up trash the items (or recycle where possible)