4. Quality Function Deployment (QFD) and House of Quality

the following content is provided under a Creative Commons license your support will help MIT OpenCourseWare continue to offer high quality educational resources for free to make a donation or view additional materials from hundreds of MIT courses visit MIT opencourseware at ocw.mit.edu I wanted to go through a little bit with you guys on what we'll expect from the group presentations and from the individual journal articles just so you guys know well ahead of time what we want you to prepare for the group presentations we're looking for fifteen to twenty minutes on what you guys have done as a group so that would be a few slides summarizing each of the weeks that we've gone through so far so the first week on what are all of your design options presented in some sort of compact way more compact than I presented in the lecture then I'd be interested to see how did you choose which design parameters are important which parts did you eliminate easily which design choices did you eliminate right away and then how did you choose your eventual design path and so if all that can be in a 15 to 20 minute coherent presentation that's great it's up to you guys whether everyone wants to present tag team or you do one person again if anyone is kind of shy I encourage you to present if anyone has some serious problems presenting I'm not going to force you to do it but I really want everyone to give it a shot so just keep that in mind as far as the journal communications I'm looking for about a thousand words focusing on what each one of you individually has done I've posted a couple of templates on the stellar site so you guys can see some examples they call them either short communications or letters to the editor so if you want to see more examples of these short journal articles you can see them online on any Springer Elsevier Wiley Journal under those sorts of names so what I'm looking for there is a bit of introduction on the design problem so that's what you guys are working on as a whole and that could be one or two paragraphs of what are you doing and why are you all doing it I'd be looking for a background section on what your team is doing so you can describe your specific problem like the core problem or the biofuels problem and some of the options available and then I'd be interested from each of you to hear what you individually have researched you know in process he did you take care of heat storage or heat exchangers what sort of design parameters have you found and what are you going to go with in the end and why this is just a way for me to see what each of you individually has been doing as well as work on some scientific communication and writing skills I forget is this a CI M class or no no okay well everything you do in the real engineering world is pretty CI M so I'd say get used to it not going to have you do as much as a CI M but it'll be a good amount and in the rest of the time it sounded like folks wanted an example of a qfd method one of these quality function development things like the house of quality would it be interest would it be illustrative to do an example of that so you guys can see how it works okay so I don't want to give anyone an unfair advantage so let's pick a problem that nobody is researching what sort of consumer item would you want to do a house of quality on anyone have any thoughts car all right car computers will what's the vote who wants to do what car raise your hands some sort of computer bicycle iPhone it's pretty pretty even car and computer and I don't have any coins to flip all right I heard car first so let's do that so this is a pretty reduced house of quality there are actually templates on the website to avoid you guys having to do any of the any of the math which is really just addition multiplication but it's time consuming the important parts of what you fill in for each of these things the first step that I usually like to take is here what I call customer requirements now usually you find your customer requirements with some sort of marketing survey to a certain market group this this whole concept was sort of borrowed from the manufacturing in and management world but it works pretty well when you're starting a big design problem like this so like I said normally we would try and figure out what the consumers want from the consumers but here you guys are going to have to guess it so what are six traits of a car that you think consumers would want fast all right what else okay safe okay sighs what sort of size this is these these are these are desires like you know I won my car to be safe I want my car to be fast so I won my car to be sighs doesn't quite work okay so is America we want big cars and this is good actually to have sort of conflicting conflicting requirements this is what happens a lot what else we're okay we're designing an SUV what else do we want okay reliable all right and one more cos I'm guessing cheek right okay so we want all of these things that clearly don't mix well with each other now um let's see I'll to sort of do this diagonally we'll have to guess the importance of each one of these can you guys close the windows there's a lot of trucks outside there all right now you guys are going to have to guess what you think the customers want in terms of importance so you guys are customers I assume some of you guys have cars is anyone have an SUV yeah okay cool so you can do this on a scale of anything to anything it's up to you how fine you want it to be it's going to become relative later so who cares what it is let's just say one to find a scale of one to five one being the least important five being the most important what do you think fast is once is most important or everyone reach a consensus three out of 500 five okay miles per gallon in an SUV I'm just I'm just uh wait what I have one yeah od we're just rating each of them on a scale of one to five doesn't you know they can all be fives if the customers think so the only reason I picked six variables is so we can finish it in this hour in reality there'll be a lot more when you guys are doing your designs I was hearing 1 & 2 4 miles per gallon which one - all right how about safe for what this is why I usually pick one market segment at a time how about big five we want our SUVs big I was just in North Carolina and boy AR I rented what I call the compact car I would describe it more as a tank I couldn't turn a corner in a parking garage I had to do three-point turns on the actual should have been one-point turns but whatever reliable or you can also say 3.5 I heard three and four you can you can make the scale as fine as you want it's all going to get relative in the end and cheap that's right we want what we can't have five okay so we have importances does anyone have a calculator okay can you talk an you find each of these in terms of percents so if we add up the total here 10 16 18 21 24 point 5 can you figure out the percentages of each of these out of twenty four point five because those are some numbers we're actually going to use Oh 20 - yep thank you well anyway if someone can just write them down I'll move on to the next step one of the next steps is figuring out engineering parameters so the customers are out there they've told you what they want in your design problems this would be electricity consumers or maybe utilities are up to you to decide but now you guys are the engineers what are some actual parameters of this car that you're going to design for examples the customer said big weight would be one of them something you can actually measure and design let's see what would some other ones be okay engine maybe engine power right I'll just put engine in watts or horsepower who cares what are some other physical parameters that you as the designers get to choose okay cost of production and this these steps can actually be some of the hardest things to figure out because you guys as a team will have to decide what you think your customers are going to want and what parameters you actually have to control by the way it can be a whole lot more than six and there are some pretty big house of quality templates out there so I need three more okay durability well is that something that's measurable I'm trying to think yeah that way okay okay so maybe expected life that's a good one we can also control the overall dimensions of the car right you can have a heavy car that's big or you can have a hollow car that's big so maybe dimensions and one more length of them this this would more be things that the engineers would be designing those oh yeah so okay so between bells and whistles and acceleration speed okay zero to 60 okay so not only is this house of quality or anything like it a good way to figure out what design parameters are most important it serves as a good catalog to catalog all your different thoughts on the interrelationships between these variables these variables and the ones in between so then I like to move to the top of the house which I'll move to the bottom there's a column here that I just like to say up or down because you can actually because you can actually put a value on each of these engineering parameters you want to just record is higher better is lower better does it not matter so for weight is heavier better or lighter better cars are safer well this is now this is all a matter of debate for you guys you could say a heavier car is safer and bigger but you could also say if you can design the same car to be lighter and how use less materials but have the same safety everything that's what you'd be going for in terms of an optimization problem so what do you guys want to do okay all right so let's say the lower the weight the better everything else kept the same so assuming same safety same acceleration same expected life if you can decrease the weight that's better for in terms of design how about engine power but yeah that should be an obvious one our cost of production lower expected life higher dimensions yeah I think we want a big car and speed that goes zero to sixty okay higher yeah of course now for the roof of the house of quality this doesn't factor in to the numerix but this does factor into trade-offs between different design parameters so it's good here to figure out what are the interrelationships between each of these parameters so further down the design path if you have to say all right we have to increase the efficiency or else nothing's going to work you can immediately see what other parameters are you going to affect and then once you have your the importances for your design parameters down here you can sort of have mental gauge of how much do you want to push one parameter at the cost of the other so for example how does weight relate to engine is it a positive correlation and negative correlation and is it strongly positive or weakly positive or negative or weakly negative more powerful well let's say in this sort of frame of mind you'd say you say if the weight of the car goes up what has to happen to the engine the engine has to get bigger right or if the if the engine gets bigger what can you then due to the weight of the car without sacrificing anything else you can make it bigger so the symbols that you'll see in this template would be two pluses for a strong positive relationship one plus for a slightly positive relationship a minus for a slightly negative relationship and two minuses for a very negative relationship you can pick whatever symbols or numbers you want but in this case I give this a plus or two pluses that's up to you guys to debate how about weight and cost of production are they necessarily correlated yeah it's a matter of debate you could say well if the car is heavier using more materials not necessarily true smarter materials could cost more per pound but if you use like an aluminum honeycomb instead of a solid steel slab to protect for protection weight can go down with cost of production so I would say we can leave this one blank just because they're not necessarily correlated how about weight and expected lifetime you know borrowing things like crashes and stuff what do you guys think I'm not hearing much which is what I was thinking - there isn't much there so you can see this can get pretty time-consuming I expect debates to happen on filling in a number of these cells but it'll be a really good thing to do if you fill it out ahead of time you guys will all understand the process between each type of variable and you'll have an agreement in your team so you won't be like well I said it should be like this well too bad the team all agreed as such that you've got to move forward how about weight and dimensions and there's no right answer here keep in mind one could say well you could have bigger hollowware car or you could say in general you increase the dimensions you're going to use more materials so it's probably not a negative correlation book you guys want to say no correlation or a slight positive or heavy positive ok so where these two meet is slight positive and weight and zero to 60 I'd say highly negative so the heavier it is the harder it is to accelerate engine and everything else kept the same and we repeat for the rest how about the engine size and the cost of production yeah so weak or strong positive it's only one component of the car so I'd say weak positive how about engine size and expected lifetime who knows engine quality is going to be like could be a big crappy engine it could be a small crappy engine it could be a big good engine could be a small good engine how about engine size and dimensions if you have a bigger engine does that necessitate larger dimensions if you have bigger dimensions does it necessitate a larger engine okay so I'm hearing weak positive okay so wherever engine and dimensions meet right here I have weak positive and how about engine size and zero to sixty that's pretty clear strong positive and we're getting down their cost of production and expected lifetime while strong or weak positive okay yeah you put a lot more good stuff in it it'll probably last longer as long as you put it together in the right way cost of production and dimensions not hearing anything so I'll just leave it like cost of production and zero to sixty acceleration okay yeah I wouldn't necessarily the same safety at a lower weight so strong or weak positive weak positive okay and home stretch in this expected lifetime and dimensions not really feeling anything expected lifetime and zero to sixty now you don't have to take into account things like the folks are going to test this zero to sixty their expected lifetime may not be very long we're just talking about the car so again I'm not hearing anything so I'll leave it blank and the last one dimensions and zero to sixty everything else keeping the same including the weight okay how come excellent strong or weak negative yeah drag goes up with velocity squared with long with area okay so now you have an agreed-upon or roughly agreed-upon framework of whether you want to maximize minimize or leave the same your parameters and the relationships between them so you can quickly refer back to this chart and start to figure out all right if I have to start increasing the weight what do I impact I impact my 0 to 60 speed how was is weight more important than 0 to 60 that's what we're going to find out right now so does anyone have those percentages ok can you read them off thirteen point three eight point nine seventeen point eight twenty two point two fifteen point six twenty two point two okay so this is one of the multipliers that we're going to be using along with this matrix now we're going to fill in this matrix of how does each design parameter affect each customer requirement this I expect to take the longest time because every single one of these cells will probably be hotly debated by you guys and not only will they be debated in your team's but when the integrators take a look at them they might say I don't know yours conflicts with yours we'll have to see about that so this is a big part of the design process and if you do this ahead of time you'll save yourselves a lot of work in the end the first thing you've got to do is agree on a scale a scale from zero to n with as many gradations between as you want what tends to show up and a lot of the templates are strong strong medium weak or no Association and I'll just use the same symbols as they do in the templates ah see this is strong medium week and none and you can assign these different weights numerical weights based on what you want to do a lot of times what I tend to see is nine three one zero and you guys can agree on any scale any fineness of scale and any amount of numbers you want as long as you guys agree on it as a team and it's consistent so we'll go through each of these and figure out what the associations are so do you guys think there's a strong medium weak or no association between the weight of the car and how fast it is strong okay how about the weight and miles per gallon okay how about the weight in the safety okay how about the weight and big strong how about weight and reliability I've heard everything from medium to weak to none so you guys got to reach a consensus on let's do a week all right meet in the middle and wait and cheap okay medium any any counter arguments to that maybe it can be out made out of all lightweight materials be really light and be really expensive okay but that can also factor into maybe cost of production so what you want to do on top as you can see some of these encompass two or more independent variables so what you want to end up doing with all of these is separating them out so that one variable doesn't encompass any others as much as you possibly can and so that's why I expect your matrix to be rather large you can think of every design parameter that you can within reason and try and make sure that they're independent but this is just sort of an exercise so onto engine in terms of horsepower and fast I think so too engine and miles per gallon okay engine size and safety I can't really think of much of an association engine size and big okay okay so you want to say medium or weak okay so we'll say weak engine size and reliability I'll go with none to engine size and cheap yeah it's a it's a big component of the car but it's only one component of the car cost of production and fast what's the relationship between those two okay I've heard it from strong to weak so we got to reach a consensus that's true so what do you guys want to say medium okay cost of production and miles per gallon I would say so too you can do a lot of more fancy engineering which costs a lot of people time to improve the efficiency of the car that could move into aerodynamics or you know fuel chemistry or fuel burning efficiency or whatever cost of production and safety medium strong medium medium medium okay cost of production and be week all right cost of production and reliability or reliable all right cost of production and cheap okay expected lifetime and fast I'm not I'm not getting anything how about you guys alright expected lifetime and miles per gallon yeah no no expected lifetime in safe okay expected lifetime and big there can be arguments you know if it's big you might clip trees it might break down more and you can have higher torque or blown over by the wind not easier I don't know what is what do you guys want to say we okay expected lifetime and reliable strong expected lifetime and cheap I'm hearing mostly medium okay medium dimensions and fast the relationship doesn't have to be positive he just has to be strength of the relationship so you can say bigger car at the same everything else slows it down a little bit but is it a little bit is it a lot up to you strong okay like I said there's no right answers till you get to the final product and you might realize that's not so good but whatever dimensions and miles per gallon so strong medium weak none medium dimensions and safe I think there's something to be said for that yeah if you're in the middle of this giant tank you know even if a car hits you from the side if its whole front goes into the car and you're not touched it's pretty cool dimensions and big I don't think I have to ask dimensions and reliable we none I'll just leave it at none dimensions and cheap all right finally zero to 60 and fast oh ok you have to choose what's fast do you think the customer is talking about top speed anything the customer is talking about response and how it feels fast yeah strong okay yeah and keep in mind you may you know these customer requirements may not be voiced in the best way it's sort of if you were designing a product and actually handing out a survey it would be up to you to frame the questions to get the information you're looking for not necessarily the answers you want but the correct information out of the customer zero to sixty and miles per gallon you got a super-fast card like burning gas now okay yeah I'd buy that but I'll say yeah let's say medium zero to sixty and safe doesn't necessarily have to be correlated you can have a fast car that's got great safety systems and we're already dealing with safe in terms of the other variables so what a fat would a car that accelerates faster necessarily be safer or less safe not necessarily heywhat yes well that depends on the drivers response time right okay so you want to put an association what strength association you're out running a velociraptor zero to sixty and big medium strong there's certainly something there medium zero to sixty and reliable yeah yeah zero to sixty in cheap super-powered cars usually yeah there's something there so would you say strong medium or weak medium all right so each of these associations has a numerical value and you'll multiply them by the percent importance according to the customers and end up summing them down here so you'll end up with a importance and then you'll just normalize it to get percent importance and it's this row right here that'll help determine a lot of your design choices what to focus on the most what to focus on first what to sort of leave by the wayside or whether you can leave it by the wayside so let's multiply this out who's got that calculator yep nine by thirteen point three plus nine by eight point nine plus three times seventeen point eight am I going too fast plus nine by twenty two point two plus one by fifteen point six plus three by twenty two point two five-thirty it's hard for me to write so I'm just going to round it so we can actually see the numbers you guys actually see those numbers okay good all right ready next for engine power nine by thirteen point three times nine by eight point nine times oh sorry add just twenty two point two and add twenty two point two two forty four next up cost of production three by thirteen point three plus nine by eight point nine plus three by seventeen point eight plus one times twenty two point two plus nine times fifteen point six plus nine times twenty two point two five 36 all right life expectancy nine times seventeen point eight plus twenty two point two plus nine times fifteen point six plus three times twenty two point two three eighty nine dimensions nine times thirteen point three plus three times eight point nine plus three times seventeen point eight plus nine times twenty two point two plus one times twenty two point two 4:22 alright so zero to sixty nine times thirteen point three plus three times eight point nine plus one times seventeen point eight plus three times twenty two point two plus three times twenty two point two two ninety seven okay so if you could sum those up and get the percentages I'll add one more aspect to this house of quality to help you sort of compare options yeah this one 535 yeah sorry my handwriting gets worse as it gets smaller so that's why I tend to do things pretty big I'll show you one sort of aspect of this house of quality that you can add on to help you graphically show how different options you could compare with size up so let's say we do it like so we want to compare three up what are what are six makes of SUVs I don't know any of them honestly okay the crossover add two more h2 and Tahoe hi heard okay all right so this is a this is the point where you could actually do a survey in turn inside your company or a survey of your customers or just guessing your design team how to each of these cars shape up with customer requirements so you can see which car sort of fits the bill the best and you know which car and let's say you had yours here you're designing a new SUV us let's just pick some random ratings because it doesn't really matter let's say I'm gonna sign a scale from zero to five let's say it's pretty fast it's got terrible miles a gallon it's super safe because it's huge it's fairly reliable and it's not cheap how would you guys or anyone that knows how would you rate the crossover in terms of these customer requirements how fast is it not okay how efficient is it one two five - okay how safe is it for okay how big is it for not the biggest okay how reliable is it three and how cheap is it three all right the h2 how does the shape-up how fast is the h2 jeez I'm guessing it's not not much better than efficiency either well I was gonna say one or two okay how safe is it okay five and big I'm guessing it's a tank all right how reliable is it we can even save 3.5 I've heard everything from 2 to 4 or averaging around about that and how cheap was it to 11.5 okay never actually owned a car so I'm not much good at this how about the Tahoe I heard okay let's say 2.5 how about miles per gallon oh not bad for an SUV how safe is it it is a big yeah okay I'm gonna guess is that about right oh all right shows what I know how reliable is it four and a half I heard fours and fives how cheap was it three all right so this sort of gives you a good idea on how your SUV compares against some of the competitors it's just a way of getting it all in there and try and figure out what are the real discrepancies between the design you're looking at and all the others are there big or small discrepancies how do they weight according to customer requirements so something that we're obviously lacking that a lot of the other cars have would be miles per gallon and cost so we're lacking it in about the same amount maybe we're lacking a little more cost than miles per gallon so if you had to say all right if I had to spend time improving anything at the sacrifice of anything else we're all along you know roughly on par with reliability or ours is a little bigger maybe doesn't have to be maybe you can decrease the size of it and somehow decrease the cost by switching to some crappier material or some heavier material which might cut down on the speed which we've got way much of an advantage over so it gives you one big giant open house of ways to help look at what you think the customers want we you as the engineering team once you can also put some other columns like degree of technical difficulty you can decide how hard is it to switching gears a bit increase the efficiency of your actor increase the total power output of the reactor increase the yield of biofuels increase the size of the tahoe or whatever you're designing so it's a good way to get everything in there at once and I also recommend that once you guys make this that y'all sign it because that's what will happen and a lot of companies out there the engineers agree on something they move forward in that path and that removes a lot of personal liability for someone can say oh I didn't agree with this choice I didn't agree with that choice well you did sign your name so it's what the team decided like it or not you did agree to it and like I said if you do this sort of stuff and early in the design process that saves you a lot of headache and arguments later on so does anyone have any questions about the house of quality yeah themself and we big one for the entire class or I don't know if you can if you want to create one for the entire class you can I think it'll be Oh yeah it certainly would be and it certainly will be a lot of work so it'll be up to you guys to decide you know you can look at each of the I would say every team should meet together and do something like this there are other qfd ways there are other of there are other ways of gauging importance you don't have to use the house of quality this is just one that I've used before so it's familiar but has anyone out there has anyone found any other ones out there yet okay well you can use this one you can find a different one you can make up your own if you can justify your choices and what I would say especially for the integrators is you can put all four teams qfd charts side by side see if anyone conflicts with anyone else if there are no conflicts you might not have to make and one for the entire group but if you want to for completeness or if you start to find big conflicts between what the Corps is trying to do and what the process heat folks are trying to do or some other two or three groups you might want to make a big one and it'll be up to you as the integrators to say alright we've analyzed every team's progress and importance we've noticed the following conflicts we'd like to make an executive decision and say we're going to focus more on this parameter than that parameter for reasons ABC so it is up to you the the focus area leads as well as the integrators to sort of define your management style I don't like the word management but I can't think of a better your your integration style yeah that's up to you and that will dictate a bit of how the design process goes is everyone included does everyone have a voice does do people have too much of a voice and it tends to just be sort of tug-of-war with sixteen or seventeen different ropes and the world never really moves far from the center at some point you may choose to make an executive decision just be sure to let everybody know so we're all on the same page so does anyone have any questions about do you guys know what you want it should be doing during this week or is it not that well defined yet or somebody tell me they don't really know okay oh you do know okay all right well for those that didn't want to answer I would say meet with your team's figure out what are all of the major engineering design parameters that you can vary what are all the major outcomes that the customer would see and start picking importances in interrelationships and maybe by Friday or Monday at the latest have one of these filled out so you have an idea of what you want to go for so during next week you can use this information to pick your one chosen design path and whatever one comes in second or third place try and quantify how far behind it is so if you want to switch in the end if you run into some unforeseen unscalable wall you'll know oh we can pick our second choice because it was just barely not as good or I don't know we should really try and make this work because everything else was left in the dust

Channel: MIT OpenCourseWare

Views: 301,961

Rating: 4.8704581 out of 5

Keywords: engineering design, requirements, QFD, quality function deployment, House of Quality, tradeoff

Id: u9bvzE5Qhjk

Length: 44min 13sec (2653 seconds)

Published: Tue Jul 24 2012