The eight types of was­te in lean manu­fac­tu­ring and how to avo­id them with the help of digi­tal tools!

Lean manu­fac­tu­ring often refers to the seven or eight types of was­te. The­se eight types of was­te (muda) refer to inef­fi­ci­en­ci­es in pro­duc­tion or assem­bly pro­ces­ses. Howe­ver, asso­cia­ted manu­fac­tu­ring are­as such as mate­ri­als manage­ment or main­ten­an­ce can also be affec­ted by was­te. The goal of cer­tain lean manu­fac­tu­ring approa­ches is to redu­ce this was­te in value-adding and sup­port­ing pro­ces­ses. This reduc­tion can levera­ge signi­fi­cant pro­duc­ti­vi­ty poten­ti­al, but it can also impro­ve manu­fac­tu­ring qua­li­ty. And as ever­y­whe­re whe­re was­te is eli­mi­na­ted, cos­ts also decrease, as mate­ri­al, time or other effort is saved. 

It is the­r­e­fo­re wort­hwhile to know exact­ly what types of was­te the­re are and which tools can be used to avo­id them! In this artic­le, we will glad­ly share this know­ledge with you and show you how digi­tal tools can increase effi­ci­en­cy poten­ti­al in pro­duc­tion and pre­vent waste.

What are the types of waste?

The eight types of was­te in lean manu­fac­tu­ring can be remem­be­red very well by the fol­lo­wing mne­mo­nic device:

D  O  W  N  T  I  M  E

The indi­vi­du­al let­ters each stand for a type of was­te: Defect, Over­pro­duc­tion, Wai­ting, Non-Uti­li­sing Per­son, Trans­por­ta­ti­on, Inven­to­ry, Moti­on and Extra Pro­cess. By eli­mi­na­ting was­te, pro­duc­tion down­ti­mes can be mas­si­ve­ly redu­ced. In the fol­lo­wing, we would like to explain each of the­se was­tes and pro­vi­de you with tools for mini­mi­zing them.

Checkliste Verschwendungsarten

1. Defect

Defects — or defects in Ger­man — are errors that can occur during the manu­fac­tu­re of a pro­duct. The­re are dif­fe­rent cau­ses for defects and addi­tio­nal resour­ces are nee­ded to cor­rect them. Defects in pro­ducts can never be com­ple­te­ly ruled out, but orga­niza­tio­nal mea­su­res can be taken to mini­mi­ze them.

Pro­ces­ses should always be desi­gned in such a way that defects do not occur in the first place. This prin­ci­ple is cal­led poka-yoke in the con­text of lean manu­fac­tu­ring. For exam­p­le, assem­bly fix­tures can be desi­gned so that com­pon­ents can only be instal­led in one pos­si­ble ori­en­ta­ti­on. Auto­no­mous qua­li­ty assu­rance, the so-cal­led Jido­ka prin­ci­ple, can also be used to detect and eli­mi­na­te defects in good time. Through in-line inspec­tion of cer­tain work steps, faul­ty assem­bly can thus be detec­ted direct­ly at the point of value crea­ti­on and rec­ti­fied immediately.

Ano­ther lean manu­fac­tu­ring method is the use of “stan­dard work”. This method invol­ves the detail­ed descrip­ti­on and pre­sen­ta­ti­on of important infor­ma­ti­on about the manu­fac­tu­ring pro­cess. It breaks down the work into work steps descri­bed in small detail. In Ger­man, this is often descri­bed as Werk­eras­sis­tenz. This ensu­res that the worker can find all the infor­ma­ti­on he needs for a repeata­ble work­flow direct­ly on site and can get help quick­ly with spe­ci­fic questions.

2. Over­pro­duc­tion

Over­pro­duc­tion usual­ly occurs when employees on the shop flo­or do not have an over­view of the over­all pro­cess. They then pro­du­ce so much at the indi­vi­du­al work­sta­tions that the fol­lo­wing work­sta­tions are over­loa­ded. As a result, inter­me­dia­te sto­rage faci­li­ties are quick­ly over­fil­led and the mate­ri­al inven­to­ry in the work-in-pro­gress increa­ses ste­adi­ly. Thus, over­pro­duc­tion ties up con­sidera­ble amounts of working capi­tal and can lead to other types of waste.

The was­te type over­pro­duc­tion can be mini­mi­zed by bet­ter plan­ning and coor­di­na­ti­on of the assem­bly pro­cess. By using a Kan­ban sys­tem, a pull prin­ci­ple can be estab­lished in pro­duc­tion, which even makes inter­me­dia­te sto­rage unnecessary.

Publicly dis­play­ing takt times and the remai­ning takt time of all work­sta­tions can also help mini­mi­ze over­pro­duc­tion. Using an Andon board, the takt time and many other key figu­res can be dis­play­ed on lar­ge dis­plays on the shop flo­or. Thus, every employee knows how much time is left until the com­ple­ti­on of the work step and bot­t­len­ecks beco­me visi­ble and can be eliminated!

3. Wai­ting

Wai­ting times are fun­da­men­tal­ly not value-adding. Employees are idle during this time becau­se they have to inter­rupt work for some reason. The­se wai­ting times can be cau­sed by mate­ri­al defi­ci­en­ci­es at the work­sta­tions. But mal­func­tions in ope­ra­ting equip­ment such as machi­nes or tools can also mean that work has to be inter­rupt­ed. Last but not least, the­se inter­rup­ti­ons can also be cau­sed by a lack of know­ledge on the part of new employees under­go­ing trai­ning if they have ques­ti­ons about cer­tain operations.

Impro­ving com­mu­ni­ca­ti­on chan­nels on the shop flo­or can mini­mi­ze the­se wait times. Ad-hoc noti­fi­ca­ti­ons of miss­ing mate­ri­al can enable mate­ri­als manage­ment to pro­vi­de the requi­red mate­ri­al as quick­ly as pos­si­ble. Like­wi­se, by report­ing ques­ti­ons from workers digi­tal­ly, the shift or pro­duc­tion mana­ger can quick­ly inter­ve­ne and take coun­ter­me­a­su­res. In this way, pro­duc­tion down­ti­me can be signi­fi­cant­ly redu­ced. By eva­lua­ting the reasons ente­red for the inter­rup­ti­ons, tar­ge­ted pro­cess impro­ve­ments can sub­se­quent­ly be imple­men­ted. This increa­ses the capa­ci­ty and qua­li­ty of the assem­bly pro­ces­ses. In our white­pa­per on alarm manage­ment, you will find more infor­ma­ti­on on com­mu­ni­ca­ti­on chan­nels in manu­fac­tu­ring environments.

4. Non-Uti­li­sing Person

This type of was­te is not actual­ly one of the seven ori­gi­nal types of was­te in terms of the Toyo­ta Pro­duc­tion Sys­tem. Nevert­hel­ess, ina­de­qua­te­ly trai­ned assem­bly employees have a signi­fi­cant impact on the pro­duc­tion qua­li­ty and capa­ci­ty of a manu­fac­tu­ring pro­cess and the enti­re orga­niza­ti­on. Howe­ver, it is not only a lack of know-how (for exam­p­le, from new or fre­quent­ly chan­ging employees), but also unre­co­gni­zed talents or igno­red impro­ve­ment ide­as that har­bor con­sidera­ble poten­ti­al for was­te. If the­se talents or impro­ve­ment ide­as are not hee­ded, this has a direct impact on the moti­va­ti­on and com­mit­ment of indi­vi­du­al employees.

Pos­si­ble solu­ti­ons to the­se chal­lenges include the use of worker assis­tance sys­tems. With the help of such digi­tal tools, infor­ma­ti­on rela­ting to the assem­bly pro­cess can be acces­sed direct­ly at the indi­vi­du­al work­sta­tions via touch panels. This appli­es, for exam­p­le, to work ins­truc­tions in the form of pdf docu­ments, check­lists, images or vide­os. The­se docu­ments, which are nor­mal­ly only acces­si­ble in the form of paper docu­ments, help new employees in par­ti­cu­lar to fami­lia­ri­ze them­sel­ves with the assem­bly pro­ces­ses. But even vete­ran employees often have a need for such infor­ma­ti­on in the case of rare­ly manu­fac­tu­red or very com­plex vari­ants of the pro­ducts. The fast and uncom­pli­ca­ted pro­vi­si­on of the­se docu­ments ensu­res that they are used and do not just gather dust in drawers.

5. Trans­port

Trans­port includes all move­ments of mate­ri­al within a pro­duc­tion pro­cess. This con­cerns raw mate­ri­al, indi­vi­du­al assem­blies but also finis­hed pro­ducts. Delay­ed or sub­op­ti­mal trans­port of mate­ri­al can cau­se a varie­ty of pro­blems, inclu­ding pro­duc­tion stop­pa­ges. In addi­ti­on, dama­ge to pro­ducts can cau­se pro­duct qua­li­ty to suf­fer. The­se nega­ti­ve effects of trans­por­ta­ti­on pro­ces­ses stem from a varie­ty of cau­ses. Poor fac­to­ry lay­out can lead to long and con­fu­sing trans­por­ta­ti­on chains. In addi­ti­on, poor­ly ali­gned manu­fac­tu­ring pro­ces­ses can cau­se mate­ri­al to pile up in inter­me­dia­te sto­rage and hin­der the pro­duc­tion process. 

Com­mu­ni­ca­ti­on tools also play a cri­ti­cal role in this type of was­te. Manu­fac­tu­ring employees can be slow to report mate­ri­al shorta­ges if the right tools are miss­ing. Logi­stics employees then react too late to indi­vi­du­al trans­port orders and pro­duc­tion has to be inter­rupt­ed until the mate­ri­al has been delivered.

A value stream map­ping can be used to crea­te a pic­tu­re of the sequen­ti­al flow of raw mate­ri­als or assem­blies. This makes it clear at which points in pro­duc­tion pro­blems with mate­ri­al sup­p­ly are to be expec­ted. Pro­ces­ses can then be impro­ved on this basis. Ano­ther opti­on is to intro­du­ce com­mu­ni­ca­ti­on tools that allow employees to report mate­ri­al shorta­ges at an ear­ly stage. Auto­ma­tic moni­to­ring of mate­ri­al invent­ories via sen­sors at the rem­oval faci­li­ties can lead to auto­ma­ti­cal­ly set dri­ving orders for logi­stics. By mea­su­ring the times bet­ween noti­fi­ca­ti­on and deli­very of the requi­red parts, the logi­stics chain can also be more fine­ly plan­ned and optimized.

6. Inven­to­ry

Was­te in the inven­to­ry, i.e. in the sto­rage faci­li­ties, is cau­sed by an unneces­s­a­ri­ly high mate­ri­al stock in the indi­vi­du­al warehou­ses of the pro­duc­tion. One cau­se is the incor­rect plan­ning of safe­ty or reor­der stocks. Ano­ther cau­se is that the pro­duc­tion speed is not adapt­ed to demand. Unre­lia­ble sup­pli­ers or long set­up times can also be the cau­se of inven­to­ry waste.

By using lean manu­fac­tu­ring tools such as Kan­ban, mate­ri­al inven­to­ry can be adjus­ted to cus­to­mer demand. This pull prin­ci­ple can dra­sti­cal­ly redu­ce mate­ri­al invent­ories in the goods-in and goods-out are­as, but also bet­ween work­sta­tions. This signi­fi­cant­ly redu­ces the amount of capi­tal requi­red for raw mate­ri­als, inter­me­dia­te pro­ducts and finis­hed pro­ducts. Mate­ri­al manage­ment can also be impro­ved via just-in-time or just-in-sequence deli­very to indi­vi­du­al assem­bly sta­ti­ons. Here again, digi­tal com­mu­ni­ca­ti­on tools play an important role. By pro­vi­ding needs-based, ear­ly feed­back on assem­bly steps, the mate­ri­al requi­red for the next work­pie­ce can be made available with precision.

7. Moti­on

This type of was­te descri­bes unneces­sa­ry, non-value-adding move­ments of mate­ri­al or peo­p­le in the manu­fac­tu­ring pro­cess. A work­sta­tion that is not opti­mal­ly set up, whe­re the distances to neces­sa­ry tools or com­pon­ents are too gre­at, leads to employees spen­ding a lot of time on non-value-adding move­ments. This increa­ses cycle times and employee moti­va­ti­on also decrea­ses due to a cer­tain level of frus­tra­ti­on. Ano­ther con­side­ra­ti­on of this type of was­te is unneces­sa­ry wal­king when report­ing mal­func­tions or mate­ri­al needs. Even loo­king at prin­ted work ins­truc­tions or dra­wings on the shop flo­or can lead to time being wasted.

Lean pro­duc­tion methods such as 5S pro­vi­de a reme­dy here. This method ensu­res that work sta­ti­ons are well orga­ni­zed. The 5 “S” here stand for the Japa­ne­se terms

Vor allem der Punkt Sei­ketsu (Stan­dar­di­sie­ren) kann durch ein Werk­eras­sis­tenz­sys­tem mit detail­lier­ten Arbeits­be­schrei­bun­gen, Zeich­nun­gen oder Check­lis­ten unter­stützt wer­den. Dadurch wird es neu­en Mit­ar­bei­tern schnell mög­lich, sich in die Arbeits­ab­läu­fe ein­zu­fin­den. Aber auch erfah­re­ne Mit­ar­bei­ter pro­fi­tie­ren durch ein Nach­schla­ge­werk für kom­ple­xe oder sel­ten gefer­tig­te Pro­duk­te und Varianten.

8. Extra Process

Exces­si­ve pro­ces­sing of pro­ducts always takes place whe­re an ope­ra­ti­on is per­for­med twice. This can be cau­sed by poor docu­men­ta­ti­on of pro­duc­tion steps or a lack of coor­di­na­ti­on bet­ween pro­ces­ses. For exam­p­le, data on a work step is recor­ded twice, the work­pie­ce is clea­ned at seve­ral work­sta­tions or more C‑parts are used than neces­sa­ry. The stan­dar­diza­ti­on of pro­ces­ses can eli­mi­na­te this type of was­te as far as pos­si­ble. This includes clea­ning up pro­ces­ses with a view to unneces­sa­ry docu­men­ta­ti­on or dupli­ca­te pro­cess steps.

This is ano­ther area whe­re the Lean Manu­fac­tu­ring method 5S , which we dis­cus­sed in the pre­vious point, comes into play. By stan­dar­di­zing work­sta­tions and sel­ec­ting unneces­sa­ry ele­ments in pro­ces­ses and at work­sta­tions, dupli­ca­te pro­ces­ses can be easi­ly iden­ti­fied and adjus­ted. This type of was­te can also be addres­sed through Kai­zen and the sim­pli­fi­ca­ti­ons of pro­cess flows that come with it.


How do digi­tal tools help you eli­mi­na­te the types of waste?

Many of our cus­to­mers start by making the eight types of was­te in lean manu­fac­tu­ring visi­ble. This is usual­ly done via a digi­tal alarm and dis­play sys­tem. The workers at the work­sta­tions are ther­eby enab­led by means of a touch panel to report errors in or ques­ti­ons about the pro­duc­tion pro­cess. This makes the­se mes­sa­ges visi­ble to the pro­duc­tion or shift super­vi­sor. The super­vi­sor can then react quick­ly and take appro­pria­te action. By sto­ring and eva­lua­ting the mes­sa­ges, opti­miza­ti­ons can be made sub­se­quent­ly to the assem­bly sta­ti­ons, the ope­ra­ting equip­ment and the pro­duc­tion processes.

A second step for many of our cus­to­mers is a worker assis­tance sys­tem. Here, docu­ments such as dra­wings, check­lists, pic­tures or vide­os are dis­play­ed at the indi­vi­du­al work­sta­tions, describ­ing the pro­duc­tion pro­cess in detail. In addi­ti­on, data on the pro­cess or the pro­duct (e.g. seri­al num­bers, mea­su­red values from test sys­tems and much more) can be recor­ded and made eva­luable. The times requi­red for a par­ti­cu­lar assem­bly step also beco­me trans­pa­rent in this way, enab­ling detail­ed clo­cking out of indi­vi­du­al work­sta­tions and the enti­re line.

When intro­du­cing such digi­tal tools, howe­ver, it is important to think big but start small. Other­wi­se, employees on the shop flo­or and in sup­port­ing are­as can quick­ly beco­me over­whel­med. Fur­ther­mo­re, it is important to invol­ve know-how car­ri­ers of the manu­fac­tu­ring pro­ces­ses alre­a­dy in the plan­ning pha­se. The­se are abo­ve all the employees in pro­duc­tion! They know what often cau­ses pro­blems and which pro­cess steps are unclear or whe­re errors often occur.

Curious now? Cont­act us, we will be hap­py to advi­se you!