Quincunx WD-7 +kuljetuskotelo

Quincunx WD-7 kovassa salkussa

Helposti kuljetettava Quincunx toimitetaan kovassa salkussa. Quincunx on mitoiltaan 4 x 37 x 72 cm.

Quincuxin yläosassa on helmisäiliö. Helmien irrotusvipu pudottaa viisi helmiä jokaisen ”vedon" yhteydessä tai yksittäin. Liikkuva suppilo, joka edustaa muutoksia prosessiin tai muutosta keskiarvossa, on jousikuormitteinen ja pitää sitä paikallaan, kunnes suppiloa siirretään/säädetään. 

SPC-ohjauskortin näkökulmasta, muutos suppilossa on ”erityissyy” vaihtelu. Piikit piikkilohkossa simuloivat ”satunnaista" vaihtelua prosessissa. Säädettävillä tapilla piikkilohkossa voi muodostaa neljä eri jakaumaa.
http://en.wikipedia.org/wiki/File:Vecchi_281.jpg

Kanavayksikössä kanavat on maalattu valkoiseksi paremman havaittavuuden takaamiseksi luokassa. Jokaisessa WD-7 Quincunxissa on myös kolme porttia, jotka pitävät helmien muodostamat jakaumat paikallaan vertailun mahdollistamiseksi. Kestävälle pleksi kannelle voidaan tehdä merkintöjä vesipohjaisilla merkkauskynillä tai kaavio-teipeillä kuvaamaan esimerkiksi toleransseja tai nominaaliarvoa.

Yksi keskeisistä avaintekijöistä laatujohtamisessa on jatkuvan parantamisen käsite. Uusi WD-7 quincunx on neljännen sukupolven malli, joka tukee tämän konseptin demonstrointia.

Uudessa Quincux WD-7 mallissa on seuraavat uudistukset:

• Pienempi ja herkempi porttilukot
• Parempi suppilo, jossa on jousikuormitus, joka pitämään sitä paikallaan
• Aukeava takatuki

What is a Quincunx...and how do you pronounce it?

The Quincunx (pronounced quinn-cux) or bead board, as some call it, was developed by a mathematician named Galton in the late1800's. The device works by dropping a series of acrylic balls, or beads, through rows of located pins. Each bead, as it hits a pin, has a 50-50 chance of falling to the left or right. When the beads pass through all the of pins

they fall into a slot or cell. The shape of the beads' distribution forms what looks like a bell shaped or 'normal curve'.

As any statistics student will tell you, a large number of populations of data or industrial processes will form what is technically called a 'normal distribution'. A true statistician will also tell you that the bead distribution in a quincunx is actually a 'binomial distribution'. However, since the binomial and normal distributions look so much alike, we are safe in mathematically treating Quincunx distributions as if they are normally distributed.

Quincunx Demonstrations

The uses of a Quincunx are only limited by the ingenuity of the instructor. Once you use a Quincunx and see how effective it is in communicating statistical concepts, you'll never teach without one. The following is a sample of the types of demonstrations that are possible:

DEMONSTRATE STATISTICAL INFERENCE -

Can statistics really predict an outcome based on a sample? Demonstrate this by running a sample of 35 beads, calculate the mean and standard deviation and predict the six standard deviation limits. Try taking bets with the trainees that the next 100 beads will fall between the six standard deviation limits calculated. Run the next hundred beads and collect your bets.

DEMONSTRATE PROCESS CENTERING -

Draw specification limits on the face of the Quincunx at the 5th and 20th column. Set the funnel to the left or right and demonstrate how a certain percentage of the measurement will fall outside of the specification. Now center the funnel and repeat the experiment. Watch the light bulbs go on with your students as they begin to understand the concept of centering a process' and how it could apply to their own processes.

DEMONSTRATE THE FUTILITY OF RANDOM INSPECTION -

This demonstration is as effective with machine operators as it is useful in showing management how they are part of the problem. Point out current random sampling techniques that have been determined by your company. i.e. check every 20th piece, every half hour, twice per shift. etc. Set up the Quincunx as in the process centering demonstration and shift the funnel near the upper limit. Point out how many operators run to the side of the tolerance so they can reduce scrap (you can always rerun the part if it is oversize but it is scrap if its undersize). Drop 19 beads then drop the 20th bead representing the inspected part and note whether it falls inside or outside the specification. Repeat the process five or six times. Chances are every bead checked will be inside the specification with about 10% of all the other beads being outside the tolerance. If a bead does falls outside the tolerance during one of the checks remind the student that most operators would run a second piece before adjusting the process. This demonstration drives home the reason why operators who are instructed to use random sampling techniques have trouble maintaining tolerance specifications.

TEACH X-R CHARTS -

Close the top gate on the Quincunx and without moving the funnel run and plot samples of five beads on an average-range control chart. Calculate and plot the control limits on the chart just as if the quincunx were a machine. After creating the control chart move the funnel and plot another sample of five parts. Students will be amazed how quickly they can detect a shift in the funnel which is analogous to a change in the process. To carry the point a little farther tape a piece of paper over the funnel portion of the Quincunx and then randomly move the funnel to different directions and let the trainees guess whether the funnel has been moved or not based on their control chart plot. This technique is very helpful in building confidence in the value of control charting. Another point can be made by sliding the funnel completely to the right and allow the beads to drop directly onto the pins. Plot another sample of 5 beads and demonstrate how the range portion of the chart detects an out of control condition. This erratic behavior is analogous to machine conditions where bearings are worn, fixtures are loose, etc.

PRE-CONTROL-

Run a sufficiently large sample to accurately calculate or predict the six standard deviation range. Mark the tolerance limits and pre-control lines on the face of the quincunx with the appropriate tape or transparency marker. Drop a series of beads with the funnel centered and demonstrate the decision rules of the pre-control plan. Move the funnel to the left or right and show how pre-control would re-center the process.

PROCESS MANAGEMENT -

The Quincunx have a narrow distribution pin block for demonstrating the effect of process improvement. Since it has less variability, the control chart demonstration will have a smaller range and consequently tighter control limits.

Huomaa myös Quality Gamebox softa, josta löytyy myös Quincunx simulaatio.