So today we're going to Deep dive into very important Concept in statistics that is process capability what is this CP CPK PP and bpk we look at all these terms in this video with the help of some animated video examples so please stay tuned don't go anywhere else just sit back relax and enjoy this video before we understand the process capability let us understand the process in simple terms process is a series of action or steps performed on input to produce an output let's check an example example describing the process of making a cup of tea from input side we have electric kettle filled with water then we process this called a brewing by adding tea and allowing water to boil in electric kettle and output could be in the form of we pouring the tea into the cup this is a very simple input output process diagram please remember almost every process can be divided into input process and output now let us understand the process capability so process capability refers to an inherent ability of a process to produce similar parts for sustained period of time under the given set of condition that is a definition of process capability but before determining the process capability we need to make sure the process is stable that means the variations observed is only due to the common cause only and no special cause of variation exist and the process is predictable and consistent over time but if the process is unstable it might exhibit certain shift Trends or cycle making it difficult to assess its process capability second is if the data is normally distributed this means that the process follows a normal distribution which we also known as the bell curve if the data collected from the process doesn't fit the normal distribution it might indicate that the process is not predictable or consistent making it difficult to assess its capability accurately once the process is both normal and stable it capability can be evaluated effectively using the various statistical method such as CP CPK PP and PPK these measures help determine whether the process can consistently mean the specific requirements and whether the adjustment of improvement are necessary we also need the large number of samples to ensure accurate and reliable assessment so in process capability we uses two indices CP CPK PP and PPK to determine whether the process is capable or not so CP and CPK are called process capability Matrix while the pp and PPK are called process performance Matrix in both these cases we want to verify if the process can meet the customer requirement that is ctq so process capability CP and CPK uses samples for evaluation and a generally short terms and tell us how the process will perform in the future while PP and bpk uses a population and a generally longterm when tell us how the process has performed in the past so CP and PP measures how well the data fits the specification limit that is upper specification limit and the lower specification limit while CPK and PPK measures how centered the data is between the specification limit let us understand this concept of CP CPK PP and PPK using some animations imagine that you're driving a car and trying to park the car in the parking space the parking space here represents the specification limit upper specification limit and the lower specification limit the car that you have its outer Dimension represents the control limit upper control limit and the lower control limit so we cannot change the specification limit because these are DED from the customer directly what we can control is the control limit that is the upper control limit and the lower control limit so let's take in the first case when the car Dimension upper control limit and the lower control limit are small and car can be easily parked inside the parking space so that means your specification limit is larger than your control limits other scenario in same situation could be the car is off centered even though it is small but it is off centered that is is likely shifted to one side of the walls which is equivalent to producing a defective part so our goal here is to make sure the car is narrower and also well centered now second case could be when the car size is almost equal to the parking space that means the specification limit is same as the control limit for this you either need expert driver to park your car without hitting the side walls and also to do that consistently for next probably 30 days or 60 days but not for a normal driver so we will be producing Parts at risk every day so some parts may go after specification some parts will still be within the specification limit this is kind of a risky scenario the third case could be when the car is too wide it won't even fit in the parking space that means your control limits are actually wider than the specification limit in this scenario you will be producing Parts which are always out of the spec and won't be accepted by the customer let's understand some more scenarios like this case where we have the specification limit so the driver here is unsteady car often scraps the wall and you will see it will produce more defective Parts unless the process width is reduced and process is centered in this case CP is equal to 7 and CPK is around 7 which is not a capable process second case could be when the your driver is still unsteady but it is better than what was in the case one he often comes too close to the boundaries the specification limits right and you are likely to have defect unless the process width here is also reduced so here the CP and CPK is though one but I would call it as a barely capable because there's always a risk of hitting the side walls third case could be when the driver is still unable to Center the car but he is consistent always too close to one side and in this case it is the lower specification limit you are likely to have a defect unless the process is centered in this case youp could be 1.5 because it is still very narrow but CPK is7 because it is shifted towards the lower specification limit the fourth case and again it is not capable the fourth case could be when the driver always Sparks successfully without scrapping the sides the process is centered as well and narrow you are unlikely to have defects even if the process shifts slightly to the other side this is the best case where CP is two and CPK is also close to two and this is the highly capable process the CP of two means S6 Sigma process Let's uh look at some formulas to calculate CP and CPK so for CP uh the formula is upper specification minus lower specification divid by process width that is 6 Sigma that is ulsl LS by 6 Sigma for CPK it is distance from mean to the nearest specification limit divided by distance from the mean to the process Edge so it is in short it is the mean of xar that is average minus lower specification limit by 3 Sigma or upper specification limit minus X barid by 3 Sigma so this is how you calculate the CP and CPK so let's take the first example to understand this concept A process has a mean of 45.5 and a standard deviation of 0.9 product has a specification of 45 + - 3 find the CP and CPK so this is the scenario so this is how we plot in the graph so we need to calculate the lower specification limmit and the upper specification limit which comes from the 45 Plus - 3 you calate lower and upper specification mean here is slightly shifted like actual mean from specification is 45 but the ACT process mean is 45.5 now let's see the formula for CP is lower upper specification minus lower specification liit by Six Sigma and CPK is mean of meanus lower specification limit by 3 Sigma or upper specification limit minus mean by 3 Sigma so whichever is less is your CPK so for CP let's put the values 14 8 which is coming from 45 + 3 and 42 is coming from 45 - 3 the specification which is given in the question by 6 into .9 so we get CP as 1.11 now for CPK uh we put the values minan as 45.5 is the process mean which is givenus 42 which is the lower specification 3 into .9 or 48 is the upper specification minus 45.5 3 into .9 so we get CP as mean of 1.3 or 0 .93 so we choose minimum value out of these two so out of which minimum is93 CPK is93 that means it is shifted towards the one side so which is not capable so we need for process to be capable we need both CP and CP K greater than one in this case even though CP is greater than one but CPK is less than one so process is not capable however by adjusting the mean if you can shift the mean process can become capable here let's Che a second example process has a mean of 70 and a standard deviation of two the product has a lower specification limit of 58 and upper specification limit of 82 now you need to find CP and CPK here so this is the scenario like you have given the lower specification and upper specification mean at 70 for CP the formula is again upper specification limit minus lower specification limit 6 Sigma we put the values we get CP as 2 let's calculate now CPK which is mean of mean minus lower specification 3 Sigma or upper specification minus mean by 3 Sigma put the values we get CP as mean of 2 or2 which is actually same so we get CPK as 2 here in this case we can say the process is highly capable because both CP and CPK are greater than one and actually it is two so it is equivalent to Six Sigma process now let's assess the brief knowledge check on this concept if you're still tuned in remember to hit the Subscribe button and press the Bell notification for all the updates from digital learning it is actually completely free for you but your supports motivate me to create more such content in the future additionally please remember to hit the like button share this video with all your friends and across different social media platforms and feel free to share any suggestions or comments that you have in the comment box below read the questions and leave your answers in the comment section below first question which of the following indices measures the potential capability of a process to produce product within the specification limit CP CPK PP and PPK question two which process capability index provides a measure of how well the process can produce within the specification limit taking into account both variability and centering CP CPK PP and PPK question three which process capability index solely assess the spread of process output CP CPK PP and PPK you can leave your answers in the comment section below [Music] [Applause] [Music]