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11/22/2011 04:43 PM
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Hi all,
I am looking for a quick an easy way to conduct a capacity study for my machine shop. We just recently purchased two new machines so we can begin to bring manufacturing back in house from offshore. Our current setup consists of 5 lathes three with barfeeders, 2 brand new swiss cnc screw machines, and 2 mills. The goal is to schedule the jobs according to the most efficient machine. Obviously the screw machines would be the way to go but we are limited to just two.
With the new purchase of these machines we are able to strategically pick which components to bring back in house. The problem is we are not sure which ones to bring in and how much. So that is where I need your assistance. I need to know my current capacity and where my max would be. Please help with spreadsheets, calculations, or any methodology that I can apply. Look forward to hearing from you.
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11/28/2011 03:42 PM
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I'd always suggest creating a scheduling board on a dry-erase board. Combine that with some observations of cycle time for each machine to build a database of cycle knowledge. You will also want to look at your product mix and how you can streamline. Can you dedicate certain, less efficient machines to certain products to eliminate/significantly reduce setup time? Are some products more complex and therefore are better suited for the newer, 'tighter' machines?
You have two approaches to consider with bringing products back in - high(er) volume or low(er) volume. In other words, which products impact your bottom line more with your equipment. If you excel at low volume, or your equipment makes changeover very simple, you may find that you can maximize revenue on the lower volume work, sending out the higher volume work to someone who will commit resources and can run it cheaper than you. Or, you can choose higher volume, which helps spread your overhead costs (assuming you currently assign costs in traditional standard costing measures per piece). There are numerous variables to consider, one of which is what path your organization wishes to take. What does the company ideal state look like? That will tell you which direction to go.
Learn what your processes can do and how they interract. That is best done through observation and OA analysis of your processes/equipment. Learn how to schedule the machines manually and efficiently before leaping to an automated scheduling system. This will allow you to understand your scheduling process and be able to find an automated system that truly does what you want, only without the waste (so many automated scheduling systems simply automate scheduling waste). There are several scheduling software options out there for jobshops looking at Lean that would be useful - ONCE you understand your system and its needs.
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12/08/2011 08:58 PM
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Originally posted by: JesseStorm
The problem is we are not sure which ones to bring in and how much. So that is where I need your assistance. I need to know my current capacity and where my max would be. Please help with spreadsheets, calculations, or any methodology that I can apply.
Jesse,
It is not easy to measure capacity of a job shop with high-mix, low-volume production. You need a method for fast and efficient what-if analysis of job shop workflow with respect to changes in resource capacities. I can illustrate one of such methods over web if you have routing information for all parts and resource requirements of every operation. The method is based on job shop scheduling logic. Mike Thelen saw the schedule output of this logic 2 or 3 years ago.
Prasad
prasad@optisol.biz
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12/09/2011 12:42 PM
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This is a typical 2nd year problem assigned to businesss degree operations management majors in university.
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12/09/2011 12:42 PM
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Prasad's software is one of those packages I was referencing. His system, while my employer didn't choose to use it, would have sped up our scheduling process (determined through the trial we ran). We had done a lot of initial work to remove the waste in our old scheduling process, as I hinted at in the above comment (understanding your system and needs). In our jobshop setting, his software would have been able to handle changes in seconds, rather than minutes or hours of work/rework.
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12/12/2011 06:00 PM
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Larry,
Your post really surprises me. In the past, I taught operations management to udergraduates of business school at a well known university in College Station, Texas, following the book on operations management by Jay Heizer and Barry Render. If you have a simple solution to the student-level problem, you can consider offering it (at least offline) to Jesse who seems to seriously need it.
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03/09/2012 01:49 PM
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Please let me know your mail i.d and i will send you the simulation sheet which will help you in maintaining the capacity planning and efficiency control of your process.
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04/05/2012 03:07 PM
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Hi Devender Mudgal,
I have a sheet that I utilize for high volume and have struggled with helping some of my suppliers on a quick and easy way to measure capacity. I'd be curious to see how your sheet matches against mine. Can you share? I'm at glen.carnahan@gmail.com
Attached is the sheet I used about 4 years ago to measure line and station capacity. It is only for 'similar too' models and is not good for mixed/low-volume models.
Many Thanks,
Glen Carnahan
Mod note: edited to attach file
Edited: 04/05/2012 at 03:07 PM by Lean Moderator
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06/13/2012 10:36 AM
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I would love to see the simulation sheet as well - thanks!
bingh1kl@cmich.edu
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08/31/2012 03:11 PM
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Hi , i would also like a copy of the spread sheet. my mail id is kdhand@micromaticgrinding.com
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09/17/2012 11:55 AM
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Hi Devender,
could you send me the capacity simulation sheet at kdhand@micromaticgrinding.com.
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09/18/2012 11:06 AM
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AlscAlessandro Scatoletti
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Hi Devender
I would like a copy too. My mail address is a.scatoletti@gmail.com.
Thanks
Alessandro
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09/18/2012 03:18 PM
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My limited experience with custom machining exposed me to the challenge of determining accurate processing times for parts that had never been made before.
While two engineers might agree on what type of machine to process the part through, different programmers could have completely different strategies for how to approach the machining sequencing. Who then is responsible for developing the time estimates for the routings? If programming is not completed until right before the part is machined, how does the organization get accurate time estimates into the system in a timely manner?
When efficiency reports came out and times were slower than the routings, it was generally considered an operator issue not an issue with determining the routing times. Having said that, my best suggestion is spend some time gaining an understanding as to how accurate the routings are and try to put in a system to improve their accuracy over time.
Our second problem was the delay in getting parts designed and loaded into the system so they could be calculated in the capacity calculations. My suggestion was to use "master generic parts" to at least get some information into the loop prior to loading the actual parts.
Timeliness and accuracy of getting information into the system is crucial for capacity planning. I'll let you guys sort out which templates and programs work best.
Good Luck
Brian
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09/21/2012 12:22 PM
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I know there were many requests earlier, but don't see any lately, for the capacity planning sheet. But, I am asking any way. Can I still get a copy? If so, please send it to michael_j_wiseman@ham.honda.com.
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10/31/2012 06:21 PM
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Many people including Jesse Rendon expressed interest to try Devender's simulation tool in Excel for job shop capacity planning. I am still curious to know how the tool is working for them because several job shops are looking for such tool. I did not see any comment on its performance until now. I am not sure that a simple Excel application can help capacity planning in a generic job shop.
Capacity planning is quite tough for small make-to-order job shops with high-mix, low-volume production, particularly when machines are multi-functional and workers have different skill sets. Those job shops want to maximize shop production performance subject to limited resources. For a brief description of job shop capacity planning, one may read our web page, Job Shop Capacity Planning .
Prasad
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11/13/2012 12:25 PM
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Hi,
can i have the capacity planning simulation sheet...
mfmalthaf@gmail.com
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11/16/2012 12:59 PM
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Hi Devender,
Would you please send me the spreadsheets
thanks in advance!
juanimorgan@yahoo.com.ar
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11/19/2012 10:54 AM
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Jesse:
We need to differentiate between planning and scheduling. For planning you need to have a straight forward SOFP (Sales, Operations, and Financial Planning) process, and this needs a rather simple capacity analysis tool. Based on forecasts, you calculate the time required to make the forecasted parts. Calculate the "waste" like scrap, rework, downtime, etc. Keep the analysis simple and use no more than 8 or 10 issues.
The day-to-day scheduling is a different matter. If this ia a job-shop operation (ie. you do not know what jobs are coming in until they get them), then the suggestion from the first respondent is good advice. Create a visual board and schedule to maximize the throughput of the entire value stream. The idea of using the most "efficient" machine is a distraction. If the machine that a job would run the fastest is busy, then run it on the machine that's available that will do the job. (in the words of the great philosopher "if you can't be with the one you love, love the one you are with") It is the total throughput of the value stream that matters, not the cost of the individual job.
if you are a genuine job shop and the SOFP process is not too relevant, then you can create a visual master scheduling process. when new jobs come in, schedule them on a board by (for example) the week. Get a rough-cut idea of the capacity vs the load. The detailed daily visual board becomes much easier to do when you have the higher level, summary plan set up in advance.
The visual rough-cut is mostly needed for giving promise dates to your customers. In some companies, the rough cut board is populated by the sale or customer service people.
BTW. These boards are called "yamazumi" in lean parlance. You might want to look on the internet. I would be happy to discuss this more deeply if it will be helpful to you.
Brian
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11/19/2012 10:54 AM
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Jesse:
I forgot the other part. You need to decide what's the right parts to bring back.
We do this with a Box Score. The Box Score shows the performance of the plant or the value stream at three levels; Operation Performance, Capacity usage, and Financial Results. We would then look at various scenarios, plug them into the box score, and to see how we can maximize the throughput - Revenue minus Direct Costs. Direct Costs are mostly materials. We would consider labor to be largely fixed costs, give or take a little overtime. And we would not be interested in applying overheads and all that nonsense.
Brian
bmaskell@maskell.com
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11/19/2012 03:04 PM
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Originally posted by: Brian Maskell
The day-to-day scheduling is a different matter. If this ia a job-shop operation, ...create a visual board and schedule to maximize the throughput of the entire value stream.
Brian,
If production scheduling in job shops is so easy, then job shops all over the world must be maximizing shop throughput with the help of visual boards.
Prasad
Optisol
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