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# PCBA Time Estimation Formula

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SMTA-Todd

PCBA Time Estimation Formula | 21 March, 2019

I am looking for a good way to estimate assembly times per board. We currently use an engineer who looks at the BOMS and gerbers, but are looking for an alternative. Any formulas or software recommendations would be helpful.

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PCBA Time Estimation Formula | 21 March, 2019

Hello,

I've done it before in Excel and it is a very simple concept. Inputs are board size, numbers of SMT and TH process sides, number of SMT and TH placements per side, boards per panel and quantity of boards to be produced. Output will be calculated based on your equipment with formulas accounting fiducial recognition time, transfer time and reflow time. In this formulas you should have "If" sentences picking the bottleneck operation of all operation in the line to make an accurate calculation. You would be surprised how accurate this tool can be. Mine was a little more complicated, as I was using it for quoting tool, so I had wages per hour, tooling costs.....and much more.

PCBA Time Estimation Formula | 22 March, 2019

Unisoft ( http://www.unisoft-cim.com / 203-913-0782 ) has software that should help.

*** Assembly Cost by Component Span Report for Quoting *** Assembly Cost by Component Span Report for Quoting http://www.unisoft-cim.com/features.htm#Assembly-Cost-Estimation-Report-for-Quoting Quote and Quality Menus video clip http://www.youtube.com/v/AHwU_hVeVGQ?start=117&end=139&version=3

*** Assembly or Parts Cost by Part Number Report *** Assembly or Parts Cost by Part Number Report http://www.unisoft-cim.com/features.htm#Component-Part-Cost-Report Quote and Quality Menus video clip http://www.youtube.com/v/AHwU_hVeVGQ?start=117&end=139&version=3

*** Solder Joint Count - Defect Per Million Operations (DPMO) Report *** Solder Joint Count - Defect Per Million Operations (DPMO) Report http://www.unisoft-cim.com/features.htm#Solder-Joint-Count-Defect-Per-Million-Operations-DPMO-Report Quote and Quality Menus video clip http://www.youtube.com/v/AHwU_hVeVGQ?start=117&end=139&version=3

PCBA Time Estimation Formula | 29 March, 2019

I am new to the community and do not know where to start.

PCBA Time Estimation Formula | 19 February, 2020

@Evtimov

My company only recently got our SMT line operational and are just starting to estimate PCBA time. I just wanted to clarify, it seems that your formula will boil down to the number of panels multiplied by the bottleneck operation. Is there more to this that I'm missing? We have been using the pick and place machine estimates as they are longer than any other operation on most of our boards. However the time estimates to complete a batch of boards has been wildly inaccurate compared to the formula estimate and I'm trying to pinpoint the missing variable.

PCBA Time Estimation Formula | 19 February, 2020

Grandpa,

You got it - Identifying the bottleneck operation is the key. The secret is to design a tool can predict accurately where this bottleneck is. In your formula you can use machine process time, PCB transportation time, part trim time, part insertion time, fiducial detection time, router de-panel time.....For board with 17 placements, I discovered that transportation of the PCB and fiducial detection is more than the placement time. Another big aspect is material. Some companies will issue work order of 100pcs with 7tape strips of 15-20 pcs for the same part number. In cases like this you can forget about machine times and formulas at all. So to sum up: Inputs should be smt sides and number of placement, TH sides and number of placement, work order size, PCBs per panel, panel size, de-paneling method. Based on this information you should be able to calculate each process time per PCB. The slowest one will give you your throughput.

PCBA Time Estimation Formula | 19 February, 2020

IPC tried to develop a standard to compare machine throughputs. The machine placement times are usually based on very few components with optimum feeder placement and a very large array of placements. Real life boards are rarely like that. Once I worked on a machine that took 5 seconds from the last part of one board until the first part of the next board. Not a big deal for panels that take five minutes. Very significant for a panel that takes 3 seconds. And are you doing timing for scheduling or costing? If you have to worry about costing for quoting purposes, then that will be a lot more work.

PCBA Time Estimation Formula | 20 February, 2020

I'm mostly looking at the time so that I can schedule. Basically I'm looking at running 1000 panels of project A and then 500 of project B. I have a limited time to get a portion of both A and B to the customer. What I am trying to confirm is whether I can run the 1000A panels and still get enough (if not all) of the 500B panels complete to ship. Hopefully reducing the set-up of the machine to only once per project.

I'm sure I will need to do costing estimates in the future but we're not currently there. Any advice you want to offer in that area is always appreciated though.

PCBA Time Estimation Formula | 20 February, 2020

If you've already run both projects on your machine, then it should be as easy as taking the run-time info out of the machine for the two projects, and adding them up. I'd round up and buffer, but, I always do :) Every PnP machine I've ever worked with will output through-put data. It's going to be your most accurate information.

If you haven't already run the projects, it'll get stickier. Most newer machines/softwares that I've seen (and it's been a couple of years since I've seen the new stuff) will have the ability to estimate the job run time. But, it is just an estimate, so, take it as an estimate...and refine it as you get actual run-time data.

As for optimizing set-up...again, most newer machines will handle this for you in software...but, again, it's only an estimate.

Cheers, ..rob