World-Class, Lean Performance Tutorials and Case Studies - Tutorial 05 scrap yard operations - scrap cans processing

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1 Wrld-Class, Lean Perfrmance Tutrials and Case Studies - Tutrial 05 scrap yard peratins - scrap cans prcessing THE PRESENT STATUS: A Scrap Yard Business cllects and prcesses scrap cl-drinks-cans fr subsequent exprt. The scrap cans cllectin/prcessing peratins cnsist f the fllwing: Scrap cans are actually delivered t the Scrap Yard by a number f "suppliers", including restaurants, htels, fast-fd utlets, small grcery shps and kisks, as well as "prfessinal" scrap items cllectrs - they cme regularly t the yard by their wn means t deliver scrap items. Scrap Cans Suppliers are classified int tw main grups: the "clean scrap" suppliers and the "dirty scrap" suppliers. "Clean scrap" suppliers include restaurants, htels and fast-fd utlets. They are classified as "clean" because their scrap cans are "clean" (frm straws - and nt mixed with glass and plastic bttles and ther nn-metal items). This kind f suppliers actually des a "srting" and separatin peratin in their premises, and their supplies cnsist nly f cans. Fr this reasn they are paid a premium price per Kg fr their supplies. "Dirty scrap" suppliers include small supermarkets and kisks and scrap street cllectrs (these last suppliers d actually earn their living by cllecting cans frm street refusal bins). They are classified as "dirty" because their supplies are generally "unsrted" (cntents include ther bjects that must be remved in the scrap yard befre prcessing). These suppliers are paid the nging market price fr scrap cans. "Clean suppliers" generally supply their gds in large refusal bags. "Dirty suppliers" supply their gds in any type f bags (generally small, supermarket-size) and even in cardbard bx type f cntainers. Suppliers arrive at the scrap yard at any randm time, and their gds are received and paid-fr immediately: they drive their vans r trucks straight t the cans prcessing area - bags and ther cntainers f cans are weighted n a scale - a small paper nte, describing items and ttal weight delivered, is given t suppliers wh can then cllect their cash payment frm the cashier's ffice n the way ut. The ffladed gds, still in their bags r ther cntainers, are thrwn by hand nt the cans cllectin area. This area is rather large and extremely messy: there are piles f multi-clur cans everywhere, as well as muntains f bags still t be pened. A map f the area is belw. 1

2 There are 3 wrkers assigned t this area. They: assist suppliers in fflading trucks and weighing the delivered gds - thrw the ff-laded gds in the cans cllectin area - when they are nt busy with suppliers they prcess cans and ther scrap nn-ferrus metal. The scrap cans prcessing peratins cnsist f: Srting cans frm ther freign bjects. This is dne in the cans cllectin area: wrkers walk between piles f cans and bags - pen small bags and ther cntainers - thrw cans in the cans pile - thrw freign bjects and plastic bags, cardbard, etc. in a big rubbish cntainer (a big cardbard bx) - bring big bags (with "clean" supplies) next t the baling area (see belw). Lading the hpper f the baling machine with cans. This is dne: either straight frm "clean" bags (that get emptied directly in the hpper) - r thrugh a big bucket, that is used t pick up cans frm the cans' pile - r even directly frm "dirty" bags, srting cans frm rubbish directly in the machine hpper. A side view f the baler/hpper/lading cnveyr is here belw: 2

3 One f the 3 wrkers, in charge f the entire area, perates the baling machine (while the ther 2 wrkers d srting and lading f hpper). He reshuffles the cans in the machine pressing cmpartment fr better cmpactin and perates manually the baler's hydraulics (pressing and ejecting). NB: the lading cnveyr can be perated bth frm the machine frnt and frm a cntrl buttn at its tp. Other activities perfrmed by the 3 wrkers include: emptying the rubbish cntainer nce a day - hammering each bale just prduced n its crners t make it fit well n a pallet - mve a full pallet f bales t the yard, fr subsequent lading nt marine cntainers fr exprt. DATA SHEET The pressing peratin cycle time is apprx. 3 minutes (it takes 3 minutes t prduce ne bale). This lng cycle time is due: primarily, t the fully manual peratin f the baler - but als due t cnsiderable time necessary t fill with cans the machine charge bx frm the hpper - and time spent in remving a bale frm the discharge cnveyr, hammering its crner, and psitining it n the pallet. The hpper can cntain enugh cans t fill the machine charge bx in ne g. Nne f the 3 wrkers is actually busy full time: all f them have cnsiderable spare time (idling, talking, waiting fr things t happen...). Apprx. 70% f the cans supplied can be cnsidered "clean" (and supplied in big bags) and 30% "dirty" (and supplied in small bags r cartns). Suppliers are very c-perative, and generally help cnsiderably the 3 wrkers fr ff-lading, weighing and psitining the supplied gds. Supplies arrive at randm times every day f the week. The verall, average amunt f cans received and prcessed in a week are equivalent t apprx. 2 full pallets f prcessed cans (bales). 1 pallet cntains 80 bales (10 layers f 8 bales per layer). The actual verall cans prcessing time amunts t an average f 2 full days per week. Hwever, the peratin is carried ut irregularly every day f the week, whenever the team decides t d it. The 3 wrkers are actually assigned t the "cans" peratin and als t ther peratins (cpper, aluminium, and stainless steel receiving and prcessing). The team has ample idle time during the week: besides resting r talking (including sme primitive frm f public relatins with suppliers) r just waiting fr things t happen (suppliers arriving with new lts f scrap), they als (try t) keep the area tidy - remve the rubbish cartns fr dispsal - and keep themselves busy at reshuffling scrap all arund. The area is very messy and really dis-rganised - als the entire prcess is very naïf and it has never been streamlined. It is felt that by applying lean principles t this peratin: Labur frce may be reduced and prductivity increased The area culd be rganised mre ratinally What can be dne? What are yur cnclusins? -- O -- 3

4 Wrld-Class, Lean Perfrmance Tutrials - Tutrial 05 deplying lean principles in nn-manufacturing peratins scrap yard peratins - scrap cans prcessing cnclusins Analysis The primary target in a case f this nature is t eliminate as much duble-handling as pssible. In the present state, the supplied gds are handled: during the ff-lading/weighing peratin (necessary) when bags are thrwn in the cans cllectin area (necessary, but can be rganised differently) fr srting - in the can cllectin area (necessary, but can be streamlined) when lading the baler hpper (necessary, but can be streamlined) A lean slutin & cnclusins must target at achieving a cntinuus as pssible flw. Hence the lean steps: Suppliers are very c-perative, and can be asked t psitin the ff-laded and weighted gds in "dedicated" areas - t the purpse the entire ff-lading area has been re-designed. "Dedicated areas" means areas that can facilitate the achievement f a cntinuus style f flw. Since the mst imprtant peratins in the prcess are "srting" (when required) and "lading hpper", these dedicated areas shuld be as clse as pssible t the machine hpper. This will create the necessary cnditins t establish the flw. Furthermre: the present srting peratin is messy and time cnsuming. This is due t the fact that srting is dne "in" the cans pile. This is very un-ergnmic: wrkers waste cnsiderable time t stretch, bend, search fr small "dirty" bags, pen them up while standing, thrw gd cans in the pile and rubbish in the rubbish cntainer, etc. The best way f srting cans is at the crrect wrking level, i.e. at hpper level (r just abve it). At hpper level means +- 1,2 m. frm the flr level: this is a very cnvenient height t wrk at ergnmically - pssibly with wrkers standing n a pedestal - and n cnditin that a wrking area is created at that height. This leads t the idea f creating the "bags strage area" at that very same level: in this way, bags can be pened and srted next t the hpper, and cans thrwn in just by sliding them. A plan and side view f the "future state area" are here belw: 4

5 The main features f the future state are: The entire "strage-areas-befre-prcessing" system has been re-designed, with "dedicated" areas fr each f the nn-ferrus materials (aluminium, cpper A, cpper B, stainless steel, and cans). Cans have a permanent strage area (see belw), whereas all ther nn-ferrus materials are stred n trlleys (tw fr each type f material). Full trlleys are brught t the baler fr pressing, n a rtatin basis. With regard t scrap cans, tw Temprary Strage Areas, respectively fr clean and dirty supplies, have been prvided n a wden stand. The 2 strage areas flr is inclined, t allw descent f bags by gravity. Bth strage areas have chipbard side walls (t prevent bags frm falling) and a frnt "stpper". Between cans strage areas and hpper, tw "srting tables" have been prvided: wrkers may cmfrtably d the srting n these tables (pssibly while standing n a small pedestal) and feed the hpper simply by "sliding" cans int the hpper. 5

6 With the new layut, it becmes pssible t re-engineer entirely the can prcessing peratin. An analysis f the Takt Time reveals that n a 5-day peratin Takt Time = 13 minutes per prcessed bale (@ 7 wrking hurs per day = 420 minutes per day = 2100 minutes per week, the Takt Time is 2100/160 = 13,1 minutes per bale). But, n a 2-day in the week peratin (as it is presently), the Takt Time becmes 840/160 = 5,25 minutes per bale. This means that if cans are prcessed cntinuusly fr 2 days, there are mre than 5 minutes t get ne bale ut. (*) With an available cycle time (srt - lad hpper - press and cmpact - hammer crners f bale - psitin bale n the pallet) f ver 5 minutes, ne wrker alne can cmfrtably implement the whle prcessing peratin. The new, ergnmic layut allws him t walk frm machine t srting tables - pen clean bags and lad the hpper - OR, pen small bags, d the srting, dispse f rubbish, and lad the hpper - then start lading the machine pressing cmpartment (there is an perating buttn at the tp f the lading cnveyr) - then walk back t the machine frnt and perate the machine fr pressing/cmpacting - then slide ut the prcessed bale - then hammer its crners, and psitin it nt the pallet. Obviusly things may be streamlined even further with an electr-hydraulic peratin f the baler and duplicated cmmands next t the srting tables. But this wuld help nly marginally (it wuld just prevent sme walking). While ne wrker prcesses cans, the ther 2 take care f suppliers, ff-lading gds, psitining, etc. Best results are achieved if the 3 wrkers are fully interchangeable (all f them trained t perate the baler). The cans prcessing peratin des nt need t be cntinuus (ver 2 full days) - it can be dne in lts f a few hurs at a time - s that als ther scrap materials may be baled every day, when required. (*) TAKT TIME - REMARKS The way the Takt Time principle has been adpted in this case is nt the classical ne. The definitin f Takt Time is = custmer demand/available time. In this case the rati supplier ffer/available time has been used instead. Yet, its use is perfectly valid, since the Takt Time is what sets the speed and pace f prductin. 6