Engineering vs Design

[Hobby73]

Can you please provide a brief explanation of the difference between engineering and design?  I hear these two terms used interchangeably, but I suspect there is a distinction.

[bson]

Technical design is part of what engineers do... in addition to many other things.

[IanB]

I would say that engineering is to apply science and technology to create something useful. Engineering may encompass design, planning, negotiation, communication, project management, people management, cost management, safety and loss prevention, legal and regulatory compliance, environmental considerations and various other things. Design is therefore one aspect of engineering.

[Brumby]

I believe it depends a lot on context - and even then, there can be subtleties that fall under the umbrella of "conventional understanding" - aka - assumed knowledge.

[Rick Law]

Can you please provide a brief explanation of the difference between engineering and design?  I hear these two terms used interchangeably, but I suspect there is a distinction.

Internal combustion Piston Engine - poor design.  Good piston engines are examples of great engineering overcoming the fault of the engine design.

Rotatory Engine is a much better design.  More efficient, much fewer moving parts...etc, etc, etc.

[Richard Head]

Rotatory?
I thought all IC engines were rotatory in nature.

[Brumby]

Not so.
The standard internal combustion engine operates through the reciprocating action of the piston.  This transverse motion is transferred to rotary motion via the connecting rod and crankshaft.

[ludzinc]

Can you please provide a brief explanation of the difference between engineering and design?  I hear these two terms used interchangeably, but I suspect there is a distinction.

Internal combustion Piston Engine - poor design.  Good piston engines are examples of great engineering overcoming the fault of the engine design.

Rotatory Engine is a much better design.  More efficient, much fewer moving parts...etc, etc, etc.

Rotary as in Wankel Rotary, or Rotary as in WW1 aircraft?

Better design?

*cough* combustion chamber seal *cough*

[tggzzz]

As recounted by an engineering professor that also lectured at a design college...

If you ask an industrial designer to design an egg:

• competent ones will produce something that is the right size, shape and colour
• good ones will also produce something that is the right weight
• none of them will produce an egg that can be eaten

[mc172]

I'm struggling to answer the question directly, as in general most people either call themselves (or are employed as) an engineer or a designer.
What is making it difficult for me to explain nicely is that engineers design things, but designers rarely engineer things. This is probably the best direct answer I can find: http://wiki.c2.com/?DesignVsEngineering

"Design" is very abstract. Engineer is over-used, such as "waste disposal engineer" = binman, "thermal enhancement engineer" = radiator fitter. Designing stuff is part of my job but I am an engineer, not a designer. Design engineer, yes, but definitely not designer. Google explains it far better than I can:

http://images.google.com/search?tbm=isch&q=designer

If I were for some reason looking to hire a designer, I would not expect them to have any technical knowledge other than how to use a computer and the most obvious difference between metal and plastic.

A good engineer (or design engineer if you will) is someone that understands a broad range of technical disciplines, such as materials science, analogue and digital electronics, physics, maths, chemistry. They won't know everything there is to know of each subject, but will or should have a pretty good, relevant understanding suffice to do their job properly and usually then some because they find it interesting. An engineer should know the difference between 316 and 316L stainless steel (the metal), for example, or ABS and PTFE (the plastic), and will be able to exploit those differences for real-world scenarios.

This is somewhat down to opinion, of course, as you will find that there are some people employed as engineers not doing anything like what I have just stated and will disagree, and vice versa.

[mc172]

Internal combustion Piston Engine - poor design.  Good piston engines are examples of great engineering overcoming the fault of the engine design.

Rotatory Engine is a much better design.  More efficient, much fewer moving parts...etc, etc, etc.

What? That is entirely opinion and mostly incorrect. I've edited your post for accuracy below:

Good piston engines are examples of great engineering

A piston engine is not a design of engine, it is a type of engine and is not an inherently poor "design".

As an example, the BMW S54B32 is a particular design of a type of engine. The engineering is the effort put into fine detail of that particular design in order to make it meet its performance goals.

What a load of utter - if Wankel engines are "superior to piston engines" because they are more efficient and have fewer moving parts, then since turbine engines are more efficient  and have even fewer moving parts than Wankel engines (they have one moving parts) I can only conclude that Wankel engines are poor, faulty designs. Convenient that I have come to that conclusion as I completely agree!

[snarkysparky]

I would say that engineering is to apply science and technology to create something useful. Engineering may encompass design, planning, negotiation, communication, project management, people management, cost management, safety and loss prevention, legal and regulatory compliance, environmental considerations and various other things. Design is therefore one aspect of engineering.

I wish they had told me this when I went into engineering.  They only mentioned the cool math and physics and creative aspect.  I absolutely hate dealing with most of the things engineering really is as you mentioned.

[ConKbot]

Anyone can do design, engineering is minimising cost/material, or maximizing the output of an already existing widget using knowledge and tools available to you.

I usually refer my gross overdesigning of mechanical or electrical things as "technicianing" (technician by title, get assigned light "engineering" work because we're shorthanded) I.e. "we need to power this with 5V 3A, can you make a converter board?" K, let me find a 6A buck converter, put an inductor so low resistance and large I know it's not gonna overheat, and put something together.   Vs engineering it which would be actually checking it to make sure the load is what they say, figuring out efficiency requirements,  and minimizing the size or cost of everything as needed, etc.

[tggzzz]

I wish they had told me this when I went into engineering.  They only mentioned the cool math and physics and creative aspect.  I absolutely hate dealing with most of the things engineering really is as you mentioned.

All jobs have aspects you don't like; deal with it. Be grateful there are some bits you do like, and that you probably have soem career options.

[tpowell1830]

If I were for some reason looking to hire a designer, I would not expect them to have any technical knowledge other than how to use a computer and the most obvious difference between metal and plastic.

Having been a good designer, I disagree that "would not expect them to have any technical knowledge other than how to use a computer and the most obvious difference between metal and plastic.". Good designers can get all of the materials and load aspects done correctly before the engineer sees the design and without input from an engineer. I certainly would not hire a designer that only had those limited qualifications. Most of the designers that I know are responsible for taking that part of the load from an engineer, whom, as pointed out, has many other duties to perform.
As a designer, I was also responsible for electrical design, and was responsible for choosing components, wire sizing, BOM, mounting of any harnesses, etc.
All that the engineer had to do with my designs was to do a cursory check that I had done due diligence, with occasional corrections, and sign off on the design.
The step below the designer would be "drafter", and I still would not hire a drafter with only those qualifications.

A designer is someone with a highly technical background that has extensive  knowledge of materials, processes, parts, components, drafting ability and often much more. Usually has a 2 year degree in the area of technical, engineering or drafting. A designer has learned his/her skills from experience along with education and works in tandem with engineers.

Despite some of the comments here that anyone can be a designer is simply not what I have seen. Designers are not quite engineers usually due to lack of degree in a university, but carry out many of the same duties.

[mc172]

I did say:

This is somewhat down to opinion, of course, as you will find that there are some people employed as engineers not doing anything like what I have just stated and will disagree, and vice versa.

If you're doing load calculations and choosing materials, you're an engineer.

[james_s]

Regarding Wankel and piston engines, "better" is subjective. The Wankel engine is certainly neat, it can produce a lot of power for the volume, it can rev very high, there are few moving parts, but it is not without disadvantages. Emissions tend to be dirty, fuel economy is poor, they have problems with rotor tip seals that were never really solved.

All internal combustion engines have relatively terrible efficiency and are full of compromises. Nobody has found anything suitable to replace them yet in applications where one needs to convert a very high energy density fuel to mechanical work in a compact and inexpensive package though.

[Rick Law]

Can you please provide a brief explanation of the difference between engineering and design?  I hear these two terms used interchangeably, but I suspect there is a distinction.

Internal combustion Piston Engine - poor design.  Good piston engines are examples of great engineering overcoming the fault of the engine design.

Rotatory Engine is a much better design.  More efficient, much fewer moving parts...etc, etc, etc.

Rotary as in Wankel Rotary, or Rotary as in WW1 aircraft?

Better design?

*cough* combustion chamber seal *cough*

Rotary as in Wankel Rotary used by Mazda RX100-RX400 series cars.  The radial arrangement of cylinders used by aircraft in WW1 and WW2 are typically called Radial Engines at least in American English (and Wikipedia).

Chamber seal for rotary engine was a problem that could be engineered out.  Besides better efficiency, the much lower parts count and simpler construction leads to fewer problems requiring heroic efforts to solve.  Piston engines too can have similar seal problems when poorly engineered.  Don't forget the Chevrolet Vega for example, it was an aluminum cylinder without steel/iron lining.  The chamber lost pressure in no time!

Just think about these two problems in piston engines for example:

(1) The intake/exhausts valves for each cylinder - at say 6000RPM, the number of open and close is huge.  The acceleration and deceleration of the valves are huge! (push up to open, relax, pull down to close).  And each valve literally crash back onto the valve seat, each time!  Each valve needs to do that twice per cycle.

(2) The piston connection to the crankshaft suffers a shock of an explosion each cycle.  Goes super compression to push the shaft.

Rotary engines has no piston, no valve, no crankshaft, etc, etc...  None of those problems exist by design.  But for the heroic effort in engineering to overcome piston engine's poor design, cars might not have came into being.

An even better example between design v engineering might have been Piston Aircraft engine verses Turboprop engine.  The comparative simplicity of the designs and the comparative efficiency/power between them are huge.  A good design leads to less engineering problems and could even lead to a more reliable product.

[james_s]

There were two types of radial aircraft engines. The early type often called a rotary engine had a stationary crankshaft while the block and cylinders rotated around it with the propeller attached to that. Later came the more conventional radial engine which has a stationary bank of cylinders arranged around a central block which is stationary while the crankshaft rotated in a conventional manner to drive the propeller.

My dad once had a Mazda with a Wankel engine, it was a fascinating bit of engineering and certainly had advantages, but it got terrible gas mileage, emission tests were not around yet or it would have really struggled to pass, and it had the usual rotor tip seal problems. There are valid technical reasons why even Mazda has given up on the Wankel for powering cars, it isn't some big conspiracy.

[max_torque]

Can you please provide a brief explanation of the difference between engineering and design?  I hear these two terms used interchangeably, but I suspect there is a distinction.

Internal combustion Piston Engine - poor design.  Good piston engines are examples of great engineering overcoming the fault of the engine design.

Rotatory Engine is a much better design.  More efficient, much fewer moving parts...etc, etc, etc.

Rotary as in Wankel Rotary, or Rotary as in WW1 aircraft?

Better design?

*cough* combustion chamber seal *cough*

Rotary as in Wankel Rotary used by Mazda RX100-RX400 series cars.  The radial arrangement of cylinders used by aircraft in WW1 and WW2 are typically called Radial Engines at least in American English (and Wikipedia).

Chamber seal for rotary engine was a problem that could be engineered out.  Besides better efficiency, the much lower parts count and simpler construction leads to fewer problems requiring heroic efforts to solve.  Piston engines too can have similar seal problems when poorly engineered.  Don't forget the Chevrolet Vega for example, it was an aluminum cylinder without steel/iron lining.  The chamber lost pressure in no time!

Just think about these two problems in piston engines for example:

(1) The intake/exhausts valves for each cylinder - at say 6000RPM, the number of open and close is huge.  The acceleration and deceleration of the valves are huge! (push up to open, relax, pull down to close).  And each valve literally crash back onto the valve seat, each time!  Each valve needs to do that twice per cycle.

(2) The piston connection to the crankshaft suffers a shock of an explosion each cycle.  Goes super compression to push the shaft.

Rotary engines has no piston, no valve, no crankshaft, etc, etc...  None of those problems exist by design.  But for the heroic effort in engineering to overcome piston engine's poor design, cars might not have came into being.

An even better example between design v engineering might have been Piston Aircraft engine verses Turboprop engine.  The comparative simplicity of the designs and the comparative efficiency/power between them are huge.  A good design leads to less engineering problems and could even lead to a more reliable product.

Don't take this the wrong way Rick, but it's pretty clear you're not a mechanical engineer!

Rotary engines are not 'more efficient' than reciprocating internal combustion engines.  They have a higher surface area to volume ratio, so a fundamentally lower overall thermal efficiency, and cannot easily leverage variable valve control and as a result again, cannot be as fully optimised as well as a typical poppet valve system.

And of course, intake and exhaust valves do not "crash" shut or open.  In fact, the losses is a typical mechanically operated poppet valve system are extremely low, just a small amount of friction and the tiny hysteresis of the valve spring. (The energy stored in the spring is returned to the camshaft on the closing flank )

[Hobby73]

This is the OP.  Thanks for all replies!

As stated above, the definition and distinction depends on the context.  You can reference engineering as a profession, or engineering as a process, or an engineer as a professional individual with a skill set.  Similar definitions can apply for design/designer.  For my purpose of wanting a brief explanation of the difference, I will state the context as the process steps within a project lifecycle. 

So at the risk of oversimplifying, but with the objective of having a succinct explanation without referencing aircraft engines, I will adopt the definitions that the design process takes functional requirements as input and produces logical and physical specs as outputs.  And the engineering process takes the specs as input and builds a new physical solution (e.g., prototype) or refines/modifies an existing physical solution as the output.  That works for me!

[xygor]

As recounted by an engineering professor that also lectured at a design college...

If you ask an industrial designer to design an egg:

• competent ones will produce something that is the right size, shape and colour
• good ones will also produce something that is the right weight
• none of them will produce an egg that can be eaten

I wonder how many inedible Cadbury Creme Egg prototypes there were.

[Rick Law]

There were two types of radial aircraft engines. The early type often called a rotary engine had a stationary crankshaft while the block and cylinders rotated around it with the propeller attached to that. Later came the more conventional radial engine which has a stationary bank of cylinders arranged around a central block which is stationary while the crankshaft rotated in a conventional manner to drive the propeller.

My dad once had a Mazda with a Wankel engine, it was a fascinating bit of engineering and certainly had advantages, but it got terrible gas mileage, emission tests were not around yet or it would have really struggled to pass, and it had the usual rotor tip seal problems. There are valid technical reasons why even Mazda has given up on the Wankel for powering cars, it isn't some big conspiracy.

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Don't take this the wrong way Rick, but it's pretty clear you're not a mechanical engineer!
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I take all constructive inputs gladly.  You are right, I am no mechanical engineer.  I am just recalling the pros and cons of the two engine types I read from auto-magazines of the era.  Since I have no dog in this fight, I will accept that yeah, perhaps rotary isn't that great a design.

That said, the two engine types (designs) clearly distinguishes the design part verses engineering that design to become a real product.

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As stated above, the definition and distinction depends on the context.  You can reference engineering as a profession, or engineering as a process, or an engineer as a professional individual with a skill set.  Similar definitions can apply for design/designer.  For my purpose of wanting a brief explanation of the difference, I will state the context as the process steps within a project lifecycle. 

So at the risk of oversimplifying, but with the objective of having a succinct explanation without referencing aircraft engines, I will adopt the definitions that the design process takes functional requirements as input and produces logical and physical specs as outputs.  And the engineering process takes the specs as input and builds a new physical solution (e.g., prototype) or refines/modifies an existing physical solution as the output.  That works for me!

And yeah it does depends on context.  I found this design vs engineering similar to strategy vs tactics.  If the agreed strategy is that "we want to control the Asia market" and decided on the tactic of "first dominates the Japanese market and then grow westward."  The executive given the task to execute the tactic will then form his own strategy on "how to dominate the Japanese market".

[vk6zgo]

Anyone can do design, engineering is minimising cost/material, or maximizing the output of an already existing widget using knowledge and tools available to you.

I usually refer my gross overdesigning of mechanical or electrical things as "technicianing" (technician by title, get assigned light "engineering" work because we're shorthanded) I.e. "we need to power this with 5V 3A, can you make a converter board?" K, let me find a 6A buck converter, put an inductor so low resistance and large I know it's not gonna overheat, and put something together.   Vs engineering it which would be actually checking it to make sure the load is what they say, figuring out efficiency requirements,  and minimizing the size or cost of everything as needed, etc.

The Tech's clunky old design will still be trundling along in 20 years time.
I give the "optimised" design three to five!

[mc172]

Rick, I'm not being a dick when I type this - I am here to learn but also impart correct information based on my knowledge. I hope you don't take this the wrong way as it is meant to be constructive.

Just think about these two problems in piston engines for example:

(1) The intake/exhausts valves for each cylinder - at say 6000RPM, the number of open and close is huge.  The acceleration and deceleration of the valves are huge! (push up to open, relax, pull down to close).  And each valve literally crash back onto the valve seat, each time! Each valve needs to do that twice per cycle.

Emphasis by me.

The acceleration and deceleration is close to sinusoidal on the open stroke and close stroke. Piston engines have valves which are forced open by a camshaft but are "pulled" back into the closed position by rather strong springs. They are not forced closed.
The transition between opening, open (stationary) and closing is somewhat less sinusoidal and is the most aggressive point of the cycle but far from "crashing" as you stated. I also note that you hint at the point at which the valve closes being the "crashing" point. Often the upper speed limit of a particular engine is set by the strength of the valve springs* - there is a fine balance between making the moving mass of the valves as low as possible and the springs very, very stiff in order to get them to close quickly and follow the closing profile of the camshaft at high speed, and reducing the parasitic friction of the valve system down to an acceptable value. The stiffer the springs, the better the valves follow the profile of the camshaft at high RPM, however the parasitic drag of the valvetrain goes through the roof and you end up using more power to drive the valvetrain than you gain by closing the valves quickly.

*It is as equally often set by the maximum inertia of the pistons and the shear strength of the gudgeon pin, which is normally made of something quite exotic and very, VERY hard. Included for completeness.

It does not matter what the absolute rate of acceleration (inversely deceleration) of the valves or anything is. As long as they are designed to be strong enough, the design is adequate.  These design challenges are present within piston and Wankel types.

There is also a point whereby the exhaust valve does not follow the close profile of the camshaft at high speed, thus resulting in a less than smooth transition between the spring closing the valve and valve being on its end stop (i.e. closed) as the camshaft is no longer modulating (or moderating) it. This is engineered deliberately in order to break up the "coke" deposits left by normal operation.

(2) The piston connection to the crankshaft suffers a shock of an explosion each cycle.  Goes super compression to push the shaft.

The burn inside a piston engine is fairly tame and is not really an "explosion". It is subsonic - the correct name is "deflagration". Both Wankel type engines and piston type engines have the exact same burn characteristics as the fuel and stoichiometric ratios are the same.  The forces are imparted to the crankshaft in the same way - close to tangentially, therefore piston engines suffer no higher peak forces when compared to Wankel engines. If anything, the Wankel engine is susceptible to higher peak loads as the bearing loads of an entire chamber burn are spread over only one tooth of the central gear. Gears tend to have load areas closer to line contacts, as opposed to approaching half a circumference of a typical connecting rod.

Rotary engines has no piston, no valve, no crankshaft, etc, etc...  None of those problems exist by design.  But for the heroic effort in engineering to overcome piston engine's poor design, cars might not have came into being.

Rotary engines have one piston per "rotor". The rotor is the piston.

Some steam engines have no discrete valves - the piston forms the valve. This does not mean it has no valves, as valves of any description naturally exhibit loss.

Wankel engines have a crankshaft, it is just not traditonally "cranked" and instead it has gear teeth cut onto it.