Jim Elwell
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Mr. S:
Your email to C regarding metric directives made its way to me, as we are both members of the US Metric Association). I am the President of an industrial manufacturing company (www.qsicorp.com) which has fully metricated its operations. This is why the email got to me: C and the President of the USMA (Lorelle Young) felt I would be the best person to respond to your questions.
By way of background, QSI Corporation is smaller than your company, but we have somewhat similar operations: we sell B2B, we manufacture a variety of equipment that includes fasteners, injection molded parts, etc. We started converting to metric about 15 years ago, and are now about 99% metric (even our secretaries use millimeters in their word processing).
With that, here are my comments on the questions you ask.
It appears the metric only is geared for the benefit of the consumer. Is this correct?
By no means is this just for the consumer. If you metricate your design process in a thoughtful, planned manner, you can reap some benefits from the conversion. In particular, most manufacturing businesses that have been around as long as yours have accumulated a wide variety of fasteners and related components (washers, nuts, PEMs, mold-in inserts, helicoils, etc.). By reviewing the volume of use of each of these, and "mapping" them to a selected set of metric fasteners, most businesses find they can reduce their part number count by half or more.
Yes, there is a transition stage (see below), but the end result is fewer part numbers and higher volume per part number. If, at the same time, you set up a review process that has to be followed before engineers can add additional parts, the "cleanliness" of this can be retained.
There is also some simplicity to be gained by moving all mechanical designs to a millimeter-based system, eliminating multiple measurements (inches, feet) and fractions (1/2, 3/4). The effect is admittedly subtle, but drawings become easier to read, mistakes from conversions largely disappear, etc. QSI's mechanical designers complained a bit when we first converted, but I suspect they would quit if I asked them to go back to feet/inches/fractions. (Oh, we do use meters for a few things, such as long cables, but otherwise everything is done in a single unit: millimeters.)
...But all of our instruments sold to both US and EU markets use English sized hardware, e.g. ¼ screws, nuts, metal and plastic tubing sizes, metal and plastic fittings, thread size, etc. As it is now, as a manufacturer of many instruments, we have a tremendous amount of this English sized hardware in stock. Converting would require us to double stock (English and Metric sized hardware) essentially for at least 10 years to support field instruments, e.g. need for replacement fittings/ferrules. In view of this, would we need to convert?
The short answer is, yes, there are some costs to converting. If you only have to support field instruments for 10 years, count yourself lucky -- we see equipment twice that old show up for repair on occasion.
The longer answer is in two parts: nominal-size parts and actual-size parts.
Nominal-size: items such as "1-1/2" tubing" where the dimension is nominal, in many cases you can just convert the label: 40 mm tubing. The accuracy of the conversion depends on how "nominal" the original measurement is. For new designs, you should also refer to metric-supply catalogs and see if they are supplying nominally similar parts, of if you need to move to (for example) 45 mm tubing.
Where we see this is with self-threading screws plastics. A #4 PLT screw can, for all practical purposes, be called an M3 PLT screw. Even though there are very small differences, the tolerances are such that #4 PLT is interchangeable with a M3 PLT.
Actual-size items, such as a #4-40 screw. Here you end up stocking two parts: the #4-40 for older equipment, and an M3 for new designs. With proper planning, the number of metric part numbers will be substantially lower than the English part numbers (as noted above), but there is no way they are interchangeable.
In the electronics world, 20 years ago everything was based on a 0.1" grid: integrated circuits, connectors, etc. Now everything is on millimeter grids (no one really had a choice but to convert), but we still have a couple old 0.1" parts hanging on. On the other hand, since everything inside our enclosures is now pretty much metric, it made a lot of sense to convert the mechanical designs also.
Many of our plastic fittings are custom made/molded (which use English sizes). To convert, we would have to design new molds using metric dimensions. I dont believe this would be necessary because its custom made and can only be purchased from us. Is this correct?
This is correct -- there is no point at all in making new molds for a custom part. At most, update your drawings to include metric dimensions. If a tool needs to be replaced, then is the time to consider whether to change any actual English dimensions (e.g., molded threads) to metric.
Replacement part numbers shown in the user manuals and sizes mentioned in the text for installation instructions would all have to be converted as well. This conversion process would cost an exorbitant amount, and having double inventory, the costs would be on-going. Will continuing to use the same English sized hardware be acceptable when the directive becomes effective 2010?
I don't know the answer to your specific question about the directive. However, regarding the rest of your question: as noted above, many of your parts will probably not have to be replaced; just update the nominal dimensions used. Also, as noted, you will not need as many new parts as you have old ones. All told, I would guess that on any parts QSI uses over which we control any dimensional feature (meaning, ignoring integrated circuits, resistors, capacitors, etc.), our part number count went up perhaps 30%. Surely nowhere near double. (In our case, since dimensioned parts are only perhaps 20% of our part numbers, the total increase in part numbers is more like 5%).
If, in your opinion we do not have to convert, after my reading much about the Metric Directive, I have deduced that since we are a US manufacturer and sell our instruments to both US and EU markets we will be permitted to indicate both Metric and English units in our brochures, catalogues, manuals, etc. Is this correct?
My understanding is that you can include both metric and English units in your documentation.
A few more points to consider:
(a) The USA is the only country left in the world that is not officially metric. Yes, there is some non-metric residual stuff in Canada and England, but with the emergence of China and India (purely metric countries) as huge markets over the next decade or so, I think it is pretty much inevitable that American companies will eventually metricate.
If that is the case, the sooner you start, the less painful it will be. I wrote an editorial about this issue that was published in Machine Design a few months ago:
http://www.machinedesign.com/asp/viewSelectedArticle.asp?strArticleId=57542&strSite=MDSite&catId=2
(b) We do not have any direct sales force in Europe, but we do have a distributor and a couple of representatives. It seems every time I meet with them, they thank us for producing metric products. They just hate having to deal with English-based products, for the converse of the reasons you list above: they have to stock two sets of fasteners, sometimes two sets of tools (e.g., wrenches). I can say with no doubt at all that making metric products gives us an edge over our competitors in Europe.
(c) As I point out in the article, if you start now, you may have the luxury of converting only NEW designs, rather than having to spend any time and money converting old products. Since QSI started metricating new designs 15 years ago, and since we sell electronics (where product lifetimes are not measured in decades), pretty much everything we build is now metric. We have old non-metric products in the field that are returned for repair on occasion, but all new products are metric only.
Anyone involved in business hates to redesign old products for a nominal benefit -- resources are just too tight for that. So, start your new designs in metric as soon as possible, and you will minimize the need to do redesigns.
(d) I cannot tell from your web site whether you do semi-custom or custom designs. If you do (my company does), then in those cases you obviously follow the lead of the customer. The vast majority of our products are sold to US customers, but many of them integrate our terminals into their equipment, then ship them overseas. Therefore, even though we sell to American companies, they are usually happy that we make metric.
That said, we also sell to some large oil exploration companies. One of these specifically requested we use English fasteners on a custom terminal we made for them. Their reason was that it was going onto an off-shore oil platform, and they did not have to stock two types of fasteners. So we made it with English screws.
I hope this answers your questions. If there is anything else I can pass on from QSI's metrication experience, please do not hesitate to contact me.
Jim Elwell
Electrical Engineer
Industrial manufacturing manager
Salt Lake City, Utah, USA
www.qsicorp.com
