{"id":878,"date":"2004-10-01T16:58:46","date_gmt":"2004-10-01T20:58:46","guid":{"rendered":"http:\/\/whizkidnine.com\/?p=878"},"modified":"2023-04-07T16:47:34","modified_gmt":"2023-04-07T20:47:34","slug":"push-linepull-line","status":"publish","type":"post","link":"https:\/\/xp123.com\/push-linepull-line\/","title":{"rendered":"Push-Line\/Pull-Line"},"content":{"rendered":"<p><strong>Goal:<\/strong> Demonstrate the difference between push (&#8220;batch&#8221;) and pull (&#8220;lean&#8221;) approaches to assembly lines.<\/p>\n<p><strong>Time:<\/strong> ~30 minutes.<\/p>\n<h2>Preparation<\/h2>\n<ul>\n<li>Get ~50 sheets of white paper and a couple of pieces of yellow paper.<\/li>\n<li>Set up four people at stations in a line, with a work area in front of each. The area between stations is the input\/output area. A\u2019s output area is B\u2019s input area.<\/li>\n<li>Teach the folders how to make an origami bird or a paper airplane. Arrange it so the first folder has a trivial job, the second folder has a fairly easy job, the third folder has to do the most work, and the last person has another trivial job (e.g., toss the airplane toward a target).<\/li>\n<li>Explain that we\u2019ll be using two different sets of work rules.<\/li>\n<li>Start the line with the \u201cpush\u201d rules, let the system run a while, and then stop them. Switch to the \u201cpull\u201d rules, let it run again, stop everybody, and debrief.<\/li>\n<\/ul>\n<h2>Push Rules (&#8220;Batch&#8221;)<\/h2>\n<p>Each person uses the same rules:<\/p>\n<ul>\n<li>If your work area is empty, take an item from your input area and work on it.<\/li>\n<li>When you finish an item, put it in your output area.<\/li>\n<\/ul>\n<p>Once a significant amount of work has piled in front of the third station, have the first station start to work on a yellow piece of paper and stop the system.<\/p>\n<h2>Pull Rules (&#8220;Lean&#8221;)<\/h2>\n<p>Each person uses the same rules:<\/p>\n<ul>\n<li>If your output area is empty and your work area is empty, take an item from your input area and work on it.<\/li>\n<li>When you finish an item, put it in your output area.<\/li>\n<\/ul>\n<p>Once a few items have come through, put a yellow piece of paper in and stop the system.<\/p>\n<h2>Debrief<\/h2>\n<p><em>What happened?<\/em><br \/>\nBring out these points:<\/p>\n<ul>\n<li>There were piles of inventory in the push system, no piles in the pull system.<\/li>\n<li>Most everybody (except the person at the end) stayed busy in the push system; people were waiting around in the pull system.<\/li>\n<li>The bottleneck person was equally busy in both cases.<\/li>\n<li>The system output was at the same rate in both cases.<\/li>\n<li>The yellow paper was way back in the push system.<\/li>\n<\/ul>\n<p><em>Productivity<\/em><\/p>\n<ul>\n<li>What is everyone\u2019s productivity?<\/li>\n<li>What is the system\u2019s productivity?<\/li>\n<li>Are they different?<\/li>\n<li>How long from when a piece of paper starts until it pops out the other end?<\/li>\n<\/ul>\n<p><em>What is waste in the two systems?<\/em> The push system has wasted inventory and time wasted in work that\u2019s not needed.<\/p>\n<p><em>How can we improve?<\/em><\/p>\n<p><em>How does this relate to software?<\/em><\/p>\n<ul>\n<li>Whether everybody is busy or not says nothing about the productivity of the system as a whole.<\/li>\n<li>Optimizing one part doesn\u2019t optimize the system.<\/li>\n<\/ul>\n<p><em>Could we get the system into balance\u2026and keep it there?<\/em><\/p>\n<p><em>How does each system respond to \u201cshocks\u201d?<\/em><\/p>\n<p><em>What if\u2026?<\/em><\/p>\n<ul>\n<li>&#8230;we switched to making a different object (e.g., birds instead of planes)?<\/li>\n<li>we used a batch size greater than one? (Will responsiveness improve?)<\/li>\n<li>we had specialized developers?<\/li>\n<\/ul>\n<p><em>Summary<\/em><\/p>\n<ul>\n<li>Lean flow suggests a pull system, not a push system.<\/li>\n<li>Constraints are exposed by people waiting (not by inventory piling up).<\/li>\n<li>It\u2019s not balance or batch size that determines whether the system is push or pull \u2013 it\u2019s whether you\u2019re driven by your input or your output.<\/li>\n<\/ul>\n<p>Toyoda was inspired by three things in setting up lean systems:<\/p>\n<ul>\n<li>knitting machines that stop automatically when there\u2019s a problem<\/li>\n<li>Henry Ford\u2019s assembly line<\/li>\n<li>American supermarkets where people push their cart around.<\/li>\n<\/ul>\n<h2>Rules Summary<\/h2>\n<p style=\"text-align: center;\"><a href=\"https:\/\/xp123.com\/wp-content\/uploads\/2004\/10\/pushline-rules.gif\"><img decoding=\"async\" class=\"aligncenter size-medium wp-image-2372\" title=\"Batch and lean rules\" src=\"https:\/\/xp123.com\/wp-content\/uploads\/2004\/10\/pushline-rules.gif\" alt=\"\" \/><\/a><\/p>\n<p><strong>Source:<\/strong><br \/>\n<span style=\"font-size: 12pt; font-family: Times New Roman;\">[William C. Wake, 2004. This writeup was for the Scrum Gathering in Denver, October, 2004. I developed this exercise based on reading about lean manufacturing, but it turned out others have beaten me to the punch; see <a style=\"color: blue; text-decoration: underline;\" href=\"https:\/\/web.archive.org\/web\/20050205031225\/http:\/\/www.mba.wfu.edu\/dsjie\/Tips\/billington.htm\">https:\/\/www.mba.wfu.edu\/dsjie\/Tips\/billington.htm<\/a> for an example. Added a picture of the rules, 9-11-2005.]<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Simulate the difference between batch and lean approaches. <a class=\"more-link\" href=\"https:\/\/xp123.com\/push-linepull-line\/\">Continue reading <span class=\"screen-reader-text\">  Push-Line\/Pull-Line<\/span><span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_wp_convertkit_post_meta":{"form":"-1","landing_page":"","tag":"0","restrict_content":""},"footnotes":""},"categories":[1],"tags":[18,35,52],"class_list":["post-878","post","type-post","status-publish","format-standard","hentry","category-xp123","tag-coach","tag-games","tag-lean"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - 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