ti : Tng quan ti liu v cc cng c thng k trong qun l cht lng SVTH : Nguyn Hu Chnh GVHD: TS Nguyn Hong Dng*

-7 cng c thng k cnh nghaV d-7 cng c thng k minh nghaV d-p dng cc cng c thng k c vo mt v d thc tXc nh nguyn nhnBin php khc phc*

Li ch ca SPC (statistical process control):-SPC l cng c ra quyt nh v gii quyt vn -Nhn din c bn cht, nguyn nhn nhng bin ng trong quy trnh, lng ha c hiu lc ca cc hot ng khc phc, phng nga v ci tinCc cng c thng k c in (Kaoru Ishikawa, 1960s):1. Lu 2. Bng kim tra 3. Biu tn s 4. Biu Pareto 5. Biu phn tn 6. Biu nhn qu 7. Biu kim sot*

Lu Bt u u voQu trnhQuyt nhu raVi k hiu c bn s dng trong lu :nh ngha : l cng c trc quan th hin qu trnh bng hnh nh, m t th t cng vic trong qu trnh to s nht qun saingKt thc*

nh ngha : l mt cng c thu thp d liu c bn ch yu gm cc con s ghi nhn v cc qu trnh

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Nh my ch bin thy sn H Long FIDICOM/c : Khu cng nghip Tn Bnh-Tp H Ch Minh Thng k s lng bch tuc yu Ngy/thng/nmBch tuc nguyn liu (block)Bch tuc yu (block)Ghi chNV kim tra

nh ngha: l mt tm tt bng hnh nh v thng k ca d liu, di dng th tn s cc i lng o v th hin phn phi d liu.

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MQH thun mnhMQH thun vaMQH nghch vaBiu phn tnnh ngha : th hin mi quan h gia cc i lng bng th. Cc i lng c lp v ph thuc c th hin bng nhng im trn th (x,y)MQH nghch mnh*

nh ngha: l th hnh xng c lit k nhng nguyn nhn c th c ca vn . Mt v d v biu nhn qu : dng 5M Vn cht lngCon ngi Phng php o lngMy mcMi trngNguyn nhn 1Nguyn nhn 2Nguyn nhn 3Nguyn nhn 2Nguyn nhn 2Nguyn nhn 2Nguyn nhn 1Nguyn nhn 1Nguyn nhn 1Nguyn nhn 1Nguyn nhn 1Nguyn vt liu*

nh ngha: l mt dng biu thanh th hin t l phn trm cc yu t nhm xc nh nhng yu t no chim t l quan trng nht. Biu Pareto c xy dng da trn nguyn tc Pareto : 20% nguyn nhn to ra 80% kt qu.

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nh ngha : l mt th biu th s n nh v khng n nh ca quy trnh theo thi gian.

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Lu Bng kim tra

Biu ParetoBiu nhn quBiu phn tnBiu tn sBiu kim sot*

Li ch:-T chc d liu t dng khng cu trc thnh dng c cu trc-Lm r tnh hung, thit lp k hoch v tm nguyn nhn gc r ca vn Cc cng c thng k mi (mt hi ng ca JUSE, 1977):

1. th quan h 2. th quan h cu trc 3. th cy 4. th ma trn 5. th phn tch d liu ma trn 6. th chng trnh quyt nh quy trnh 7. th mng hot ng

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nh ngha: l mt cng c tm kim gii php ca nhng vn c mi quan h phc tp bng cch ch ra mi quan h gia chng.

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nh ngha: l mt phng php trc quan cho vic xy dng v t chc thng tin ri rc bc l mi quan h t nhin ca chng.

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nh ngha: l cng c trc quan cho nhng vn , mc tiu v quyt nh c u tin t m. Thng tin c t chc dng cy.

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nh ngha: l mt cng c chiu di ca mi quan h gia hai hay nhiu nhm thng tin mt cch tin li v c h thng, gm mt bng m cc hng v cc ct cha cc nhn t lin quan.

L-MatrixT-MatrixC-Matrix*

nh ngha: l mt cng c xc nh mt cch c h thng nhng sai st c th xy ra bng cc bin php i ph

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nh ngha: l mt th gm cc im trn h ta (x,y) hnh thnh t vic phn chia v sp xp d liu trong th ma trn tm ra cch thc chung phn bit v to s r rng ca mt lng ln thng tin dnh chm vo nhau.

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nh ngha : l mt cng c cho php th hin s ph thuc cc nhim v v ch ra tng thi gian hon thnh nhim v, th t cc nhim v cn gii quyt*

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S liu thu c t nh my ch bin thy sn H Long (KCN Tn Bnh) trong thi gian thc tpThi gian l 20 ngyLi nghim trng nht : qu trnh cp ng (cp ng khng t yu cu, block bch tuc b yu )

p dng vo v d thc t Biu thanh th hin phn trm t l li bch tuc yu *

Biu Pareto th hin cc ngy li tp trung nhiu nhtDa vo biu Pareto, ta thy rng li tp trung ch yu 6 ngy u ca biu Pareto, chim khong 75% tng s li. Xem xt nguyn nhn tc thi: ngy 11/10 c mt t b h nn s block yu kh nhiu. Vy l vic bo tr khng tt. Bin php khc phc l sa cha ngay v thc hin vic bo tr tt hn.

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Tip theo, ta lit k cc nguyn nhn c th c bng biu nhn qu: Bch tuc yu Cng nhn Phng php o lngNguyn vt liuMy mcMi trngLng nc chmCh quanCch xp khunNhit Thi gianThm ninGii tnhBo tr*

Thm nin lm vic: vn xy ra vo cc ngy c anh cng nhn s 1 vi thm nin l 1 tun. l cc ngy 16/9, 22/9, 9/10, 11/10 v 15/10.Nguyn nhn: thiu kinh nghim lm vicKhc phc : cn c chnh sch hun luyn nhn vin mi*

Lng nc chm vo khun trc khi cp ng:-Ngy 11/10:*

Ngy 9/11:*

Ta thy :-Ngy 11/10 : c 6 im lin tc c xu hng gim-Ngy 9/10: c 2 im vt qu gii hn Bin php khc phc :Cn hun luyn li nhn vinThao tc phi chnh xc

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Thi gian cp ng:Ta thy rng gia t l li v thi gian cp ng c s tng quan kh mnh (r = -0.7976). Vy li nhiu l do thi gian cp ng t-Khc phc: iu ch thi gian cp ng t 3.8 n 4h s gim thiu c s li*

Qua lun vn ny, vi kt lun c rt ra nh sau:Hiu bit v mt s cng c thng k c v ang s dng hin nay trong cc nghnh k thut, dch v qun l cht lngTrong thi gian ngn nhng p dng v x l vn trong nh my, ng thi a ra c bin php khc phc, mc d y ch l mt v d nhThy c vin cnh ca nn kinh t nc ta khi m mi lnh vc u p dng SPC trong qun l cht lng. Lc , mi hng ha ca Vit Nam u c mt tt c cc nc trn th gii!*

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