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         程晓华(John Cheng),全面库存管理(TIM)咨询独立顾问,《制造业库存控制技术与策略》课程创始人、讲师,1995年开始接触MRP,曾在大宇重工业、顿汉布什、IBM、伟创力(Flextronics)等企业担任生产计划员、物料计划主管、高级物料经理、供应链总监、全球物料总监等职务,个人专著:《制造业库存控制技巧》、《首席物料官》、《决战库存》、《制造业全面库存管理》等,邮件johnchengbj@126.com,TIM咨询公众号:ITOOTD

 

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确实,库存管理是制造企业的重中之重--yongyu888
我就是搞信息化项目的实施工程师,也就是所谓的搞IT的。我不是你文中所太述的这种人。--Jasmine3
1--hking1
程老师有趣,像是面对面交流--刚柔流
基础数据尚做不准.--喜鹊
hhhh--爬行的蜗牛
大兵的故事有趣。有的公司的仓库主动性强的, 也会知道。他们会不断追问计划人员或采购人员。--hbenzj
赞同。这些基本概念要清楚才能在管理上有的放矢,做精细化的提升。--hbenzj
325466--钱小敏
期待后续发文。--tulipbrave
怎么看--无双之城
都知道智能化很重要,但是很多机构都是空喊口号,具体又做了些什么呢?--szhanrui
理论化的东西是一套,实际做法又是一套,在牛毛多一样的小企业里,灵活管理,损失的是一部分效益,但按部就班的做事,可能会死掉,不要总拿外企的启蒙教育国内作坊企业,[呵呵]--FUJIKUO
作者写得真好,的确如此,我想很大的原因是任正非先生想体验一下排队打的的事情,然后大脑休息一下而已。实在没有必要大惊小怪。还有不在父母身边的游子们应该常常回家看看,珍惜父母在的时间,多行孝心,少关注一些不关痛痒的小事。--信息化的小螺钉
程老师的博文 观点让我耳目一新!媒体的炒作,让大家盲目的追求。却没有认真的思考本质!--longlong899
上国外大学的在线课程,报名怎么报?英文一般的人能对付吗?--ivanstang
不建议你们自己开发ERP。--程晓华(VIP)
您好,我第一次到这个网站,发现您是供应链管理方面的专家,我们公司想自己弄一个ERP,不知道您是否有这方面软件开发的朋友,如果有,冒昧请您帮忙推荐一下。--RhettTan
发邮件给我,johnchengbj@126.com--程晓华(VIP)
多谢程老师的分享,但是云盘无法下载,请问哪里可以继续下载呢--otherall

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 Many people who have been working for many years in supply chain or materials management area, still they do not know what’s the difference between safety stock and buffer stock. Especially in Chinese, most of the case is they are translated into same Chinese terminology “安全库存” by those professors from universities, which has been confusing many people with even more than one generation. This is ridiculous but that’s the fact.

When there is any de-commitment or disasters happen to customers, always people from outside of materials organization will challenge the materials planner / buyers, why have you not set up safety stock for this part # or finished goods? Why did you not load MPS with more safety stocks? Seems that they know materials management very well, which in their eyes, materials management is just as simple as safety stock – as long as you have set up safety stock, everything will fixed! Personally I have been seeing this kind of stupid people many many years and being challenged by this kind fools many times already. Again, this is ridiculous but somehow they should not be blamed too much because they were not educated with right books.  

Just as its name implies, “safety stock” is for safety purpose, which although we have never seen real “safe” inventory to guarantee the avoidance of those unplanned accidents, like incoming quality issue, over-attrition, scrap, transportation jam-up etc. But anyway, the initial objective of safety stock was trying to find a way to secure the requirements of demand and terminate the impact from those accidents. For example, usually the machine attrition of part # A is 1%, in order to satisfy 10,000 pieces’ production, we need to buy 10,000 + 10,000 x 1% = 10,100 pieces  and that 100 piece is safety stock. But the problem is, “usually” the machine attrition rate for this component is 1%, but how to handle the case like suddenly the machine attrition rate is 5% and we do not find out timely ??  No any safety stock is safe!

We had lots of discussion on chapter 4 for buffer stock, where we say buffer stock is decided by the demand fluctuation and actually even there we used “safety stock” + average demand x replenishment cycle time as “buffer stock” calculation. That so called “safety stock” is actually “buffer stock” but not real safety stock because its formula is still considering the demand fluctuation.

Believe many people will be completely confused by reading through here. Actually, you can simply understand the different like this –

  1. safety stock is purely set up by considering the unplanned accidents, like over attrition, quality disaster etc.;
  2. buffer stock is used to cope with the fluctuation of demand – if the demand is quite stable without much fluctuation, we do not need to set up any buffer stock, maybe just a safety stock.
  3. you can easily decide the safety stock by statistics like 2% of cycle stock which is decided by replenishment cycle time x average demand, but you must calculate the buffer stock based on demand fluctuation.
  4. usually,  safety stock is useful to those inconsecutive demand while buffer stock is working under consecutive demand environment.
  5. safety stock always mean EXTRA requirement to normal demand, when you run MRP or even manually calculate the requirements for materials,  system will always ask you to pull more than needed quantity, but buffer stock is within the normal demand.
  6. below chart 14-1 may help to understand

        Chart 14-1 safety stock vs buffer stock vs cycle stock

 

发表于: 2009-06-02 13:05 程晓华 阅读(8218) 评论(5) 收藏 好文推荐

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评论列表
# re: Safety stock vs Buffer stock
2009-06-05 00:18 | 吴学强 | 1楼
很有收获,确实安全库存并不安全。细化概念有助于分析问题和解决问题。一旦出现缺料或者缺货,就归因于安全库存不高,的确是一种错误的思考方式,如果试图通过提高安全库存来解决问题就是一种片面的解决办法。
# re: Safety stock vs Buffer stock
2009-06-07 12:31 | 程晓华 | 2楼
是的,没有安全的库存;往往是高库存伴随着高缺货率。
# re: Safety stock vs Buffer stock
2009-06-11 19:32 | 【匿名用户】:E-works热心网友 | 3楼
A new book for inventory control ? Great .
# re: Safety stock vs Buffer stock
2009-06-12 13:01 | 程晓华 | 4楼
still on going, with English
# re: Safety stock vs Buffer stock
2013-03-14 09:13 | 【匿名用户】:E-works热心网友 | 5楼
非常受用。。。。。 

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