components manufacturing methods

Chalo said:

I may have left out some noteworthy processes, but at the moment I
think that's about all the common metalworking techniques used in the
manufacturing of bike parts.

Chalo

Chalo,

Thanks contributing this! Bravo!

Chalo said:

bicycle_disciple said:

What manufacturing methods are being used in high end components these
days and how do each one affect strength, failure due to fatigue,
stiffness etc?

There are more factors than manufacturing method that dictate the
properties of a part.

Know first of all that stiffness is a product of basic material type
and part dimensions, not manufacturing technique. A cast stem made
from weak, soft aluminum would be as stiff as a cold-forged and
machined stem made from 7075-T6 alloy, if they both had the same
shape, size, and weight. So for stiffness, you are concerned about
gross categories of material (e.g. steel vs. titanium vs. aluminum vs.
magnesium), part weight, and part form. It makes no difference how
the part is made.

For the purposes of the discussion, I am going to exclude frames,
forks, rims, etc-- things that can be considered structures unto
themselves. Such parts have more in common with each other than they
do with components that function as mechanisms.

The highest quality components these days are either cold forged from
metal or laid up and cured from carbon/epoxy. (I'm not going to talk
about carbon parts because I think they're goofy.) Forging is
basically smashing material into the desired shape between tools or
forms made of harder stuff. It makes the metal stronger and reduces
the size and effect of internal flaws, as well as being a material-
efficient way of making parts. The tradeoff is that the dies (shaped
tools) for forging are very expensive, and the finish quality of parts
in as-forged condition can be pretty crude.

Forging can be done on "cold" metal (in the same microcrystalline
state as at room temperature), which causes work hardening--
strengthening-- of the metal itself. It can also be done hot, with
metal that is softened and easier to smash into shape. Hot forged
parts have the structural advantages of "grain" that follows the shape
of the part and diminished internal flaws, but the metal will be in a
relatively soft state after the part cools. Thus it will be both
weaker and more ductile (bendable; the opposite of brittle) in
comparison to a cold forged part made from the same alloy. You can't
usually tell just by looking whether a forged part was cold- or hot-
forged.

The most common sort of stem I see on new bikes is forged from
aluminum around a mandrel (making the finished product hollow):

http://www.sheldonbrown.com/harris/images/stem-dimension-thless-sm4523.jpg

Most aluminum brake arms, seatpost heads, crank arms, pedal bodies,
and hub shells on decent quality bikes are also forged.

Casting allows the the same sorts of complex shapes as forging, with
even more detail and finer surface finish. (Castings can also be
incredibly crude and poorly finished.) Cast metals tend to be softer
and weaker than cold-forged metals, but much more brittle than hot-
forged metals. They also contain the largest flaws from which cracks
can propagate. Casting dies are very expensive, but the incremental
unit cost of cast parts is tiny compared to most other processes. As
a result, cast parts are common on cheap pedestrian bikes which are to
be sold in great numbers-- think Huffies and other bicycle-shaped
objects.

Machining is the term for cutting material away from a casting,
forging, or blank of raw metal. Any bike part with threads for screws
in it has been machined to some degree. Machining parts from plain
bar stock is one of the most economical ways to make small numbers of
a part, but one of the most expensive ways to mass-produce parts. It
produces a huge amount of swarf (chips) which must be recycled or
discarded.

Machining includes milling (which would be used to make a crank or
fancy chainring) and turning (which would be used to make a hub shell
or pedal spindle), as well as other processes like drilling, tapping
(making threads), broaching (making splines and keyways), flycutting,
and surface grinding. CNC stands for "computer numeric control",
meaning the machine runs under the command of a computer which has
been programmed with toolpaths by its operator. CNC machining allows
shapes and finish quality which were not feasible when the machines
were controlled exclusively by hand cranks and levers.

It's common these days for forgings to be machined on all exposed
surfaces. This accomplishes two primary things: It brings the part
to a very uniform shape and finish, and it makes the part shiny and
attractive to the consumer without the need for much more surface
treatment.

Stamping is another process that can be seen in some metal bike
parts. Stamping uses punches and dies to strike flat forms from metal
sheet or plate, sometimes bashing curved surfaces into the parts in
the same process or a subsequent step. Cheap steel single-pivot
calipers are probably the best-known stampings used in bikes, though
there are plenty of other examples. Seat guts are stamped, as are
some brake levers. Steel chainrings, sprockets, derailleurs, and hubs
are almost always stamped. Lots of steel stems are made by stamping
or a combination of stamping and welding. Pedal cages are stamped.

The benefit of stamping is entirely in its low manufacturing cost.
Parts made this way usually lack rigidity for their weight, owing to
their thin, flattened and mostly open sections.

Welding is used for some parts, like stems and a few cranks and
seatposts. Welding from sections of tube results in a naturally stiff
and efficient structure with all its mass close to the part surface,
where the material can best resist stresses. The drawbacks are
relatively high labor cost and significant variations in uniformity
and quality control. Almost all welded parts will need some amount of
machining before and after welding.

I may have left out some noteworthy processes, but at the moment I
think that's about all the common metalworking techniques used in the
manufacturing of bike parts.

Chalo

Excellent post! Thanks.

Lou
--
Posted by news://news.nb.nu (http://www.nb.nu)

Johnny Sunset aka Tom Sherman said:

Chalo Colina said:

...
I may have left out some noteworthy processes, but at the moment I
think that's about all the common metalworking techniques used in the
manufacturing of bike parts.

Chalo neglects to mention the drinking of beer [1] by the machinist
after the work is done.

[1] The skill of the machinist can be correlated to the quality of the
beer.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

or the dope smoked while it is done

Quoted message said:

Tom Sherman said:

Chalo Colina said:

...
I may have left out some noteworthy processes, but at the moment I
think that's about all the common metalworking techniques used in the
manufacturing of bike parts.

Quoted message said:

Chalo neglects to mention the drinking of beer [1] by the machinist
after the work is done.

Quoted message said:

[1] The skill of the machinist can be correlated to the quality of the
beer.

or the dope smoked while it is done

I had a boss like that once. I couldn't imagine getting any work done
that way. Seemed to work for him, though.

Chalo

Please consider for the FAQ. Answers a lot of common questions well.

Well said.

Ron

Chalo said:

bicycle_disciple said:

What manufacturing methods are being used in high end components these
days and how do each one affect strength, failure due to fatigue,
stiffness etc?

There are more factors than manufacturing method that dictate the
properties of a part.

Know first of all that stiffness is a product of basic material type
and part dimensions, not manufacturing technique. A cast stem made
from weak, soft aluminum would be as stiff as a cold-forged and
machined stem made from 7075-T6 alloy, if they both had the same
shape, size, and weight. So for stiffness, you are concerned about
gross categories of material (e.g. steel vs. titanium vs. aluminum vs.
magnesium), part weight, and part form. It makes no difference how
the part is made.

For the purposes of the discussion, I am going to exclude frames,
forks, rims, etc-- things that can be considered structures unto
themselves. Such parts have more in common with each other than they
do with components that function as mechanisms.

The highest quality components these days are either cold forged from
metal or laid up and cured from carbon/epoxy. (I'm not going to talk
about carbon parts because I think they're goofy.) Forging is
basically smashing material into the desired shape between tools or
forms made of harder stuff. It makes the metal stronger and reduces
the size and effect of internal flaws, as well as being a material-
efficient way of making parts. The tradeoff is that the dies (shaped
tools) for forging are very expensive, and the finish quality of parts
in as-forged condition can be pretty crude.

Forging can be done on "cold" metal (in the same microcrystalline
state as at room temperature), which causes work hardening--
strengthening-- of the metal itself. It can also be done hot, with
metal that is softened and easier to smash into shape. Hot forged
parts have the structural advantages of "grain" that follows the shape
of the part and diminished internal flaws, but the metal will be in a
relatively soft state after the part cools. Thus it will be both
weaker and more ductile (bendable; the opposite of brittle) in
comparison to a cold forged part made from the same alloy. You can't
usually tell just by looking whether a forged part was cold- or hot-
forged.

The most common sort of stem I see on new bikes is forged from
aluminum around a mandrel (making the finished product hollow):

http://www.sheldonbrown.com/harris/images/stem-dimension-thless-sm4523.jpg

Most aluminum brake arms, seatpost heads, crank arms, pedal bodies,
and hub shells on decent quality bikes are also forged.

Casting allows the the same sorts of complex shapes as forging, with
even more detail and finer surface finish. (Castings can also be
incredibly crude and poorly finished.) Cast metals tend to be softer
and weaker than cold-forged metals, but much more brittle than hot-
forged metals. They also contain the largest flaws from which cracks
can propagate. Casting dies are very expensive, but the incremental
unit cost of cast parts is tiny compared to most other processes. As
a result, cast parts are common on cheap pedestrian bikes which are to
be sold in great numbers-- think Huffies and other bicycle-shaped
objects.

Machining is the term for cutting material away from a casting,
forging, or blank of raw metal. Any bike part with threads for screws
in it has been machined to some degree. Machining parts from plain
bar stock is one of the most economical ways to make small numbers of
a part, but one of the most expensive ways to mass-produce parts. It
produces a huge amount of swarf (chips) which must be recycled or
discarded.

Machining includes milling (which would be used to make a crank or
fancy chainring) and turning (which would be used to make a hub shell
or pedal spindle), as well as other processes like drilling, tapping
(making threads), broaching (making splines and keyways), flycutting,
and surface grinding. CNC stands for "computer numeric control",
meaning the machine runs under the command of a computer which has
been programmed with toolpaths by its operator. CNC machining allows
shapes and finish quality which were not feasible when the machines
were controlled exclusively by hand cranks and levers.

It's common these days for forgings to be machined on all exposed
surfaces. This accomplishes two primary things: It brings the part
to a very uniform shape and finish, and it makes the part shiny and
attractive to the consumer without the need for much more surface
treatment.

Stamping is another process that can be seen in some metal bike
parts. Stamping uses punches and dies to strike flat forms from metal
sheet or plate, sometimes bashing curved surfaces into the parts in
the same process or a subsequent step. Cheap steel single-pivot
calipers are probably the best-known stampings used in bikes, though
there are plenty of other examples. Seat guts are stamped, as are
some brake levers. Steel chainrings, sprockets, derailleurs, and hubs
are almost always stamped. Lots of steel stems are made by stamping
or a combination of stamping and welding. Pedal cages are stamped.

The benefit of stamping is entirely in its low manufacturing cost.
Parts made this way usually lack rigidity for their weight, owing to
their thin, flattened and mostly open sections.

Welding is used for some parts, like stems and a few cranks and
seatposts. Welding from sections of tube results in a naturally stiff
and efficient structure with all its mass close to the part surface,
where the material can best resist stresses. The drawbacks are
relatively high labor cost and significant variations in uniformity
and quality control. Almost all welded parts will need some amount of
machining before and after welding.

I may have left out some noteworthy processes, but at the moment I
think that's about all the common metalworking techniques used in the
manufacturing of bike parts.

Chalo

Thanks for all your replies. This kept bugging me, and now it
encourages me to read more on manufacturing technologies. This
discussion was productive though.

Ron
http://cozybeehive.blogspot.com

RonSonic said:

Please consider for the FAQ. Answers a lot of common questions well.

Well said.

Ron

Chalo said:

bicycle_disciple wrote:

Quoted message said:

Quoted message said:

What manufacturing methods are being used in high end components these
days and how do each one affect strength, failure due to fatigue,
stiffness etc?

Quoted message said:

There are more factors than manufacturing method that dictate the
properties of a part.

Quoted message said:

Know first of all that stiffness is a product of basic material type
and part dimensions, not manufacturing technique. A cast stem made
from weak, soft aluminum would be as stiff as a cold-forged and
machined stem made from 7075-T6 alloy, if they both had the same
shape, size, and weight. So for stiffness, you are concerned about
gross categories of material (e.g. steel vs. titanium vs. aluminum vs.
magnesium), part weight, and part form. It makes no difference how
the part is made.

Quoted message said:

For the purposes of the discussion, I am going to exclude frames,
forks, rims, etc-- things that can be considered structures unto
themselves. Such parts have more in common with each other than they
do with components that function as mechanisms.

Quoted message said:

The highest quality components these days are either cold forged from
metal or laid up and cured from carbon/epoxy. (I'm not going to talk
about carbon parts because I think they're goofy.) Forging is
basically smashing material into the desired shape between tools or
forms made of harder stuff. It makes the metal stronger and reduces
the size and effect of internal flaws, as well as being a material-
efficient way of making parts. The tradeoff is that the dies (shaped
tools) for forging are very expensive, and the finish quality of parts
in as-forged condition can be pretty crude.

Quoted message said:

Forging can be done on "cold" metal (in the same microcrystalline
state as at room temperature), which causes work hardening--
strengthening-- of the metal itself. It can also be done hot, with
metal that is softened and easier to smash into shape. Hot forged
parts have the structural advantages of "grain" that follows the shape
of the part and diminished internal flaws, but the metal will be in a
relatively soft state after the part cools. Thus it will be both
weaker and more ductile (bendable; the opposite of brittle) in
comparison to a cold forged part made from the same alloy. You can't
usually tell just by looking whether a forged part was cold- or hot-
forged.

Quoted message said:

The most common sort of stem I see on new bikes is forged from
aluminum around a mandrel (making the finished product hollow):

Quoted message said:

http://www.sheldonbrown.com/harris/images/stem-dimension-thless-sm452...

Quoted message said:

Most aluminum brake arms, seatpost heads, crank arms, pedal bodies,
and hub shells on decent quality bikes are also forged.

Quoted message said:

Casting allows the the same sorts of complex shapes as forging, with
even more detail and finer surface finish. (Castings can also be
incredibly crude and poorly finished.) Cast metals tend to be softer
and weaker than cold-forged metals, but much more brittle than hot-
forged metals. They also contain the largest flaws from which cracks
can propagate. Casting dies are very expensive, but the incremental
unit cost of cast parts is tiny compared to most other processes. As
a result, cast parts are common on cheap pedestrian bikes which are to
be sold in great numbers-- think Huffies and other bicycle-shaped
objects.

Quoted message said:

Machining is the term for cutting material away from a casting,
forging, or blank of raw metal. Any bike part with threads for screws
in it has been machined to some degree. Machining parts from plain
bar stock is one of the most economical ways to make small numbers of
a part, but one of the most expensive ways to mass-produce parts. It
produces a huge amount of swarf (chips) which must be recycled or
discarded.

Quoted message said:

Machining includes milling (which would be used to make a crank or
fancy chainring) and turning (which would be used to make a hub shell
or pedal spindle), as well as other processes like drilling, tapping
(making threads), broaching (making splines and keyways), flycutting,
and surface grinding. CNC stands for "computer numeric control",
meaning the machine runs under the command of a computer which has
been programmed with toolpaths by its operator. CNC machining allows
shapes and finish quality which were not feasible when the machines
were controlled exclusively by hand cranks and levers.

Quoted message said:

It's common these days for forgings to be machined on all exposed
surfaces. This accomplishes two primary things: It brings the part
to a very uniform shape and finish, and it makes the part shiny and
attractive to the consumer without the need for much more surface
treatment.

Quoted message said:

Stamping is another process that can be seen in some metal bike
parts. Stamping uses punches and dies to strike flat forms from metal
sheet or plate, sometimes bashing curved surfaces into the parts in
the same process or a subsequent step. Cheap steel single-pivot
calipers are probably the best-known stampings used in bikes, though
there are plenty of other examples. Seat guts are stamped, as are
some brake levers. Steel chainrings, sprockets, derailleurs, and hubs
are almost always stamped. Lots of steel stems are made by stamping
or a combination of stamping and welding. Pedal cages are stamped.

Quoted message said:

The benefit of stamping is entirely in its low manufacturing cost.
Parts made this way usually lack rigidity for their weight, owing to
their thin, flattened and mostly open sections.

Quoted message said:

Welding is used for some parts, like stems and a few cranks and
seatposts. Welding from sections of tube results in a naturally stiff
and efficient structure with all its mass close to the part surface,
where the material can best resist stresses. The drawbacks are
relatively high labor cost and significant variations in uniformity
and quality control. Almost all welded parts will need some amount of
machining before and after welding.

Quoted message said:

I may have left out some noteworthy processes, but at the moment I
think that's about all the common metalworking techniques used in the
manufacturing of bike parts.

Quoted message said:

Chalo

Gabbing at Sebring, I expressed some wonder at the durability of
contemporary chevy can-am cars now 5 liter not 7 or more as a complete
package, racing equipment kinda DIY not factory suggesting the level
of preperation was higher than 20 years before.
But Ti and steel metallurgy was the answer, that 20 years of
metallurgy progress improved the finishing rate by 100% or more.

On Jul 28, 9:35 pm, bicycle_disciple <[email hidden]>

Quoted message said:

Thanks for all your replies. This kept bugging me, and now it
encourages me to read more on manufacturing technologies. This
discussion was productive though.

I was curious when i got into cycling, then some bike mags featured
cnc machining and I wound up taking a course and doing that for awhile
( big mistake though, I hate noise and love the outdoors, fresh air, a
challenge and freedom)

Quoted message said:

I was curious when i got into cycling, then some bike mags featured
cnc machining and I wound up taking a course and doing that for awhile
( big mistake though, I hate noise and love the outdoors, fresh air, a
challenge and freedom)

I have to say, one of the downsides to CNC machining is that it limits
the inventive process to a small subset of the folks who participate
in the process. When a machinist took a blueprint and a piece of
metal and turned cranks with his own hands, the methods and steps were
largely left up to him. Now he's more likely to get a diskette with a
set of toolpaths on it, and nothing of significance is left to his
discretion.

I think this is one of the reasons why many CNC machine shops are
small owner-operated outfits. When a man participates every part of
the process from finding new customers to shipping finished product,
he can keep his mind stimulated. When he just takes toolpaths from
somebody else and runs machinery, it's pretty difficult to maintain
any enthusiasm for the work.

Chalo

Chalo said:

Quoted message said:

I was curious when i got into cycling, then some bike mags featured
cnc machining and I wound up taking a course and doing that for awhile
( big mistake though, I hate noise and love the outdoors, fresh air, a
challenge and freedom)

I have to say, one of the downsides to CNC machining is that it limits
the inventive process to a small subset of the folks who participate
in the process. When a machinist took a blueprint and a piece of
metal and turned cranks with his own hands, the methods and steps were
largely left up to him. Now he's more likely to get a diskette with a
set of toolpaths on it, and nothing of significance is left to his
discretion.

I think this is one of the reasons why many CNC machine shops are
small owner-operated outfits. When a man participates every part of
the process from finding new customers to shipping finished product,
he can keep his mind stimulated. When he just takes toolpaths from
somebody else and runs machinery, it's pretty difficult to maintain
any enthusiasm for the work.

very true. and added to that, without experienced machinist/shop work
input, serious design mistakes can be made. just like modern engineers
seem to have lost any ability to design to their material, they seem to
have no /clue/ about production process - and cnc production is the
/prime/ culprit responsible. same for production method to reduce costs.

jim beam said:

Chalo said:

When a man participates every part of
the process from finding new customers to shipping finished product,
he can keep his mind stimulated. When he just takes toolpaths from
somebody else and runs machinery, it's pretty difficult to maintain
any enthusiasm for the work.

very true. and added to that, without experienced machinist/shop work
input, serious design mistakes can be made. just like modern engineers
seem to have lost any ability to design to their material, they seem to
have no /clue/ about production process - and cnc production is the
/prime/ culprit responsible. same for production method to reduce costs.

In my experience working with a couple of hotshot high-tech startups,
some engineers are able to accept suggestions from a "laborer", and
some just can't for whatever reason. It seems like a pass/fail issue
of basic engineering competence to me, but then... I'm not in
management.

If a design engineer can't take suggestions from someone below his
station, then it doesn't really matter whether there is a functioning
feedback mechanism or not. The problem is partly technological, as
you point out, and partly cultural. If we as a technological society
could surmount it, I bet we could resume our former status as the best
innovators in the world. But as our whole society becomes more
stratified, rank becomes more important and ability less so. The
decadence of technology turns out to be just another aspect of the
decline of empire.

Chalo

Chalo said:

jim beam said:

Chalo wrote:

Quoted message said:

Quoted message said:

When a man participates every part of
the process from finding new customers to shipping finished product,
he can keep his mind stimulated. When he just takes toolpaths from
somebody else and runs machinery, it's pretty difficult to maintain
any enthusiasm for the work.

Quoted message said:

very true. and added to that, without experienced machinist/shop work
input, serious design mistakes can be made. just like modern engineers
seem to have lost any ability to design to their material, they seem to
have no /clue/ about production process - and cnc production is the
/prime/ culprit responsible. same for production method to reduce costs.

In my experience working with a couple of hotshot high-tech startups,
some engineers are able to accept suggestions from a "laborer", and
some just can't for whatever reason. It seems like a pass/fail issue
of basic engineering competence to me, but then... I'm not in
management.

If a design engineer can't take suggestions from someone below his
station, then it doesn't really matter whether there is a functioning
feedback mechanism or not. The problem is partly technological, as
you point out, and partly cultural. If we as a technological society
could surmount it, I bet we could resume our former status as the best
innovators in the world. But as our whole society becomes more
stratified, rank becomes more important and ability less so. The
decadence of technology turns out to be just another aspect of the
decline of empire.

Chalo

a lot of assemblies are farmed out to be manufactured as component
parts, so one has the faintest clue it might be for...but then again,
you have to understand that anyone who designs and builds "stuff"
wouldn't want anyone taking liberties with their design. one of my
places qc had a problem keeping the specified tolerance on a part and
after many costly attempts to better rectify the situation the
production manager submitted a formal request that the tolerance
standard be opened to the next level which we were achieving- the
answer was a resounding "no !" and after about 4 months or so the
contract went to someone else- the point being, what is "good enough"
ain't necessarily "good".

Quoted message said:

Chalo said:

jim beam said:

Chalo wrote:
> When a man participates every part of
> the process from finding new customers to shipping finished product,
> he can keep his mind stimulated. When he just takes toolpaths from
> somebody else and runs machinery, it's pretty difficult to maintain
> any enthusiasm for the work.
very true. and added to that, without experienced machinist/shop work
input, serious design mistakes can be made. just like modern engineers
seem to have lost any ability to design to their material, they seem to
have no /clue/ about production process - and cnc production is the
/prime/ culprit responsible. same for production method to reduce costs.

In my experience working with a couple of hotshot high-tech startups,
some engineers are able to accept suggestions from a "laborer", and
some just can't for whatever reason. It seems like a pass/fail issue
of basic engineering competence to me, but then... I'm not in
management.

If a design engineer can't take suggestions from someone below his
station, then it doesn't really matter whether there is a functioning
feedback mechanism or not. The problem is partly technological, as
you point out, and partly cultural. If we as a technological society
could surmount it, I bet we could resume our former status as the best
innovators in the world. But as our whole society becomes more
stratified, rank becomes more important and ability less so. The
decadence of technology turns out to be just another aspect of the
decline of empire.

Chalo

a lot of assemblies are farmed out to be manufactured as component
parts, so one has the faintest clue it might be for...but then again,
you have to understand that anyone who designs and builds "stuff"
wouldn't want anyone taking liberties with their design. one of my
places qc had a problem keeping the specified tolerance on a part and
after many costly attempts to better rectify the situation the
production manager submitted a formal request that the tolerance
standard be opened to the next level which we were achieving- the
answer was a resounding "no !" and after about 4 months or so the
contract went to someone else- the point being, what is "good enough"
ain't necessarily "good".

great example - the designer and producer should have been able to
figure this out. done right, either the design gets fixed or the
producer throws in the towel - it's stupid to leave it unresolved and
shift contractor where the same problems will reoccur.

jim beam said:

Chalo said:

Quoted message said:

I was curious when i got into cycling, then some bike mags featured
cnc machining and I wound up taking a course and doing that for awhile
( big mistake though, I hate noise and love the outdoors, fresh air, a
challenge and freedom)

I have to say, one of the downsides to CNC machining is that it limits
the inventive process to a small subset of the folks who participate
in the process. When a machinist took a blueprint and a piece of
metal and turned cranks with his own hands, the methods and steps were
largely left up to him. Now he's more likely to get a diskette with a
set of toolpaths on it, and nothing of significance is left to his
discretion.

I think this is one of the reasons why many CNC machine shops are
small owner-operated outfits. When a man participates every part of
the process from finding new customers to shipping finished product,
he can keep his mind stimulated. When he just takes toolpaths from
somebody else and runs machinery, it's pretty difficult to maintain
any enthusiasm for the work.

very true. and added to that, without experienced machinist/shop work
input, serious design mistakes can be made. just like modern engineers
seem to have lost any ability to design to their material, they seem to
have no /clue/ about production process - and cnc production is the
/prime/ culprit responsible. same for production method to reduce costs.

On another planet a long, long time ago I took a CNC programming class (complete
with punched tape) student instructions were first tested by "machining"
styrofoam blocks held in place with wooden clamps. One way to save tool costs in
case of error. I think it was considered more instructive to let them see the
destruction than to just hand it back with a mark through the obvious bad path.

Ron

jim beam said:

done right, either the design gets fixed or the producer throws in
the towel - it's stupid to leave it unresolved and shift
contractor where the same problems will reoccur.

How did you come to this assessment, given the little information
that was given?

Obviously the contract started with the specified tolerances for the
part in question and the vendor accepted them, probably with the
idea to be able to meet them inside his business model. Maybe he
misjudged his quality abilities and someone else does not, maybe
with a different business case.

--
MfG/Best regards
helmut springer

Chalo said:

In my experience working with a couple of hotshot high-tech startups,
some engineers are able to accept suggestions from a "laborer", and
some just can't for whatever reason. It seems like a pass/fail issue
of basic engineering competence to me, but then... I'm not in
management.

If a design engineer can't take suggestions from someone below his
station, then it doesn't really matter whether there is a functioning
feedback mechanism or not. The problem is partly technological, as
you point out, and partly cultural. If we as a technological society
could surmount it, I bet we could resume our former status as the best
innovators in the world. But as our whole society becomes more
stratified, rank becomes more important and ability less so. The
decadence of technology turns out to be just another aspect of the
decline of empire.

There used to be a lot more apprentice-mode learning in engineering
professions, and this used to mitigate the white/blue collar gap. The
main reason that this has disappeared is the same reason that
engineering disciplines have become more narrowly specialized -- the
pace of technical change. The phenomenon is observable in all the
technology driven fields (e.g. medicine). People simply don't have the
time for breadth, it's all they can do to maintain depth.

Another factor is passion. Many of today's technical professionals were
attracted by a paycheck. Only so many "naturals" are born, the rest are
just recruited to fill the slots. The "natural" engineers I've met all
had terrific hands-on skills, mostly because they were passionate enough
to get their hands dirty, having engineering as both a vocation and
avocation.

The best innovation comes from the combination of breadth and passion
with the prerequisite creativity and depth. Individuals with all that
have always been rare. Perhaps they're getting rarer, but with only so
many to go around, lucrative fields brain drain less lucrative ones, and
the faster the field is evolving the less time anyone has for anything
other than narrow specialization, so the inter-specialty and blue-white
collar gaps widen. If you see a bad blue-white gap, your particular
organization likely falls into one of those two camps
(drained-traditional or tech-race).

Helmut Springer said:

jim beam said:

done right, either the design gets fixed or the producer throws in
the towel - it's stupid to leave it unresolved and shift
contractor where the same problems will reoccur.

How did you come to this assessment, given the little information
that was given?

Obviously the contract started with the specified tolerances for the
part in question and the vendor accepted them, probably with the
idea to be able to meet them inside his business model. Maybe he
misjudged his quality abilities and someone else does not, maybe
with a different business case.

you might be right - wouldn't be the first time. but you might not.
the point is, successful manufacturing requires practical feedback from
the production team, not just one-way traffic from the design team. if
they're making mistakes, they need to know about it and work with it -
not just assume incompetence and move on to another producer that will
likely run into the same problem.

Helmut Springer said:

jim beam said:

done right, either the design gets fixed or the producer throws in
the towel - it's stupid to leave it unresolved and shift
contractor where the same problems will reoccur.

How did you come to this assessment, given the little information
that was given?

Obviously the contract started with the specified tolerances for the
part in question and the vendor accepted them, probably with the
idea to be able to meet them inside his business model. Maybe he
misjudged his quality abilities and someone else does not, maybe
with a different business case.

--
MfG/Best regards
helmut springer

when a part is for a car and that part has to be recalled because of
either a design or manufacturing error it's tens of millions of
dollars in charges for the maker- and for the consumer, when you need
to replace a part you expect the replacement part to fit- you don't
care about the manufacturing difficulties invovled. however,
sometimes difficulties can impinge on the design- look at the aztec,
the back end of that car is about the ugliest designs on the road, but
according to another discussion I had, it is the result of an
inability to get the manufacturing technology to work with the design,
so the design was changed in order to resolve the issue.

jim beam said:

the point is, successful manufacturing requires practical feedback from
the production team, not just one-way traffic from the design team. if
they're making mistakes, they need to know about it and work with it -

Yes.

Quoted message said:

not just assume incompetence and move on to another producer that
will likely run into the same problem.

You seem to indicate that this assumption was made here, how did you
come to that assumption of yours?

--
MfG/Best regards
helmut springer

Helmut Springer said:

jim beam said:

the point is, successful manufacturing requires practical feedback from
the production team, not just one-way traffic from the design team. if
they're making mistakes, they need to know about it and work with it -

Yes.

Quoted message said:

not just assume incompetence and move on to another producer that
will likely run into the same problem.

You seem to indicate that this assumption was made here, how did you
come to that assumption of yours?

er, because there was a problem? either they didn't qualify the
producer sufficiently or they didn't address production issues sufficiently.