Mold maintenance and date codes?
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  1. #1
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    Default Mold maintenance and date codes?

    Question for those in molding. A lot of plastic parts will show a little round month calendar with a pointer on them. I assume this is for noting when the mold was last serviced but it had me curious how are these things used in the real world?

    I would have thought dates mean very little in the scheme of things vs number of cycles a mold runs. Is that typically tracked too? What actually is changed on molds when maintenance is done or do they just wear out till they need replacement? Just a curiosity of mine that I am sure others here could elaborate on.

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    Date stamps are actually used to mark when the parts were molded and not for maintenance on the mold. Main reason for them is to easily trace tooling and processing defects, for example if its 09/21 and you found out that part molded in 08/21 has a tooling defect(broken ejector pin, flash, whatever) then you can assume that all the parts produced after that point have the same defect.

    Maintennace on molds in done based on number of cycles(tool opening and closing) and can be traced by simple counter.
    Cycle counter for optimum process data monitoring | HASCO Portal
    You can also get a rough idea about cycles from production/ stock data.

    If its simple preventative maintenance then its simply cleaning the mould and replacing greases and flushing cooling circuit.
    You would also check the mould throughout, so anything could be replaced if needed.
    If its major maintennace then you would go as far as regrinding parting lines and vents, changing pillars and bushes, polishing cavities etc.
    Where I work, standard parts like sprue bushes, ejector pins, locks, wear plates are replaced either when they break, create problems or wear is found during preventative maintenance.

    Hope this helps.

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    What Kamil said.

    Some moulds I’ve worked on were so old they had the date clock replaced a few times…

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    Kamil,

    Thanks for the explanation. That answers some of my curiosity but wasn't what I was thinking. How often do you guys inspect parts as they come off of a molding machine?

    Seems like in your explanation an enormous amount of parts would need to be scrapped if you are going off effected days of bad production. I would have thought in high volume production one would want to catch defects a lot faster maybe sampling by the hour at least?

    I will have to take a closer look but the most recent item I was looking at was a made in China pants hanger. I think the thing only had a month dial on it. I wouldn't be surprised in a large facility like that if they are shooting 1,000,000+of those things across multiple machines per week or definitely per month.

    What good does knowing the production month do for them at that point? That would be a lot of scrap if you had to toss all of April!

    Anyhow thanks for shedding some light on this its something I have observed a lot over the years and always wondered about.

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    We don't run date codes we run by shot count. After so many shots the mold is fully cleaned and inspected. Since a lot of our molds use ceramic cores we also look for excessive wear from core bumpers and core contact points such as pins and locators.

    Our parts are 100% xrayed in wax and after casting and some even get cat scanned. They also go through dye penetrant testing, cmm, and laue (for grain structure). Some also get destructive testing.

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    Adammil,

    Our quality team does first offs and then patrol checks all the machines every hour during day shift(this is marked on production paperwork attached to every machine). We only work 8-5PM, but run most automatic jobs overnight, so morning check are very important.

    Patrol checks involve visual inspection, checking with bespoke gauges and CMM inspection if required.

    Date stamps are more useful if something squeezes past you and your customer to 3rd party where original packaging is lost(no batch number available).


    We have one customer who repackages products when they arrive at his factory. He also doesnt consume oldest parts first, but rather uses whatever we send him most recently (we didn't know about this to start with). We were having constant compaints for particular problem we thought was solved in the past... he kept finding it every time he got through to that batch. Unfortunately tool didn't have any date stamps to start with :P


    As for Chinese pants hanger... I've got some experience with chinese toolmakers/moulders. Some things they do simply don't make sense.

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    How are those pointer date stamps put in the molds and how do they change the dates?

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    In auto parts you want to keep up with your stamps because that’s how far back you are going to eat parts if there is a recall. The date is changed every time the die or mold is run.
    Don


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    I know that. My question is what is the mechanism to change the pointer position?

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    A whole new insert goes there and the old one put back in the tackle box to be reused later on
    Don


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    Quote Originally Posted by D Nelson View Post
    A whole new insert goes there and the old one put back in the tackle box to be reused later on
    Don


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    I know we change core id's and other inserts out for others...some are held by screws on the side, some slide out in a block, and some need the whole damn mold half disassembled...some disassemble from the top and some have to come apart from the bottom...what a pain sometimes.

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    Quote Originally Posted by Superbowl View Post
    How are those pointer date stamps put in the molds and how do they change the dates?
    The assemble is press fit into a pocket, hopefully with a knock out hole beneath it. The date is changed by a little arrow that turns in the assembly with a screwdriver, when the year is over the center portion with the arrow will unscrew and you can insert a new year without mold disassembly. I have seen on diecast molds that have a grid pattern and the mold operator just hits the mold with a punch for the new date, or week, or month to put a ding into the part.


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