Did I Pay Right Price For My Mold In China

I am always amazed at the discussion when people start talking about the price of an injection mold. One thing I have learned after 40 years in the industry is that there is nothing more expensive than a cheap mold. How can it be that the  prices quoted for the same tool can vary by so much when all I am asking for is a x-cavity mold for a subject part. There are many cost drivers when quoting a new tool.

What does the mold look like.  In many cases asking mold makers to bid on a new mold is like going to a home builder and stating that you want a 3 bedroom, 2 bath house with a 2 1/2 car garage and wanting the price. There is way too much information missing. Many home builders simply will not supply a quote until they have a design to look at. Give 5 shops the same part print and 3D part file and all 5 many see this mold entirely differently  depending upon how the RFQ was written. The best way to get an accurate quote is with a complete list of specifications and a preliminary design or sketch. The clearer the information that more accurate the quotes.

Materials can be a big cost driver. There are typically two types of mold suppliers.  One supplier focuses only on having the lower possible price. These  mold makers  typically cut every corner they can to be able to provide the lowest cost. This can mean buying the lowest priced steel they can find. They will purchase the cheapest grades of carbon for making electrodes. They will make the mold base as small as possible to save $50 to $100 on steel. This could easily mean a mold base that will flex and move under injection pressure. The other type of mold supplier is one who is focused on quality. They tend to purchase the best grades of steel, install better quality components and design molds that are more robust.

One item that can add a substantial amount of cost is inserting. It can be very easy for a mold maker to cut the part geometry directly into the cavity and core blocks without inserting certain features. Inserting anything means having to accurately machine a pocket in the right location and then manufacture an insert that matches up correctly to the surrounding part geometry. Why would anyone want to insert something when it can be cut directly into the solid block? First off you insert features because the area can be much more effectively vented during part filling. Venting is probably the most important functional item in a mold and many times the most overlooked and misunderstood feature by mold makers. You can't get the plastic in if you first don't get the air/gas out. You also insert areas because they are fragile and the tendency is that over time the steel will fatigue and need to be replaced. It is much easier and less costly in the long run to insert fragile areas when the mold is being built verses after the mold has broken and the steel needs to be restored, not to mention that if it isn't designed in from the beginning you might have screw holes or waterlines in the way. 

How much cooling is required? If it costs $3-$4 an inch to drill waterlines in a mold and an uneducated mold maker recommends a simple one layer of water the molder may pay a big penalty everyday the mold runs. The best water schematic might mean 3 layers of water with baffles. The cooling cycle is by far the longest portion of the total cycle time of an injection mold. Non-uniform cooling besides leading to cycle times that are longer that required, can also cause stress in the part which can increase shrinkage and warpage related problems. I have always been amazed at the lack of focus by molder on optimizing the mold cooling schematic. They tend to leave so much money on the table. 

The other big cost driver is quality. Let's take the mold base for instance. You can purchase a pre-made mold from many sources. You can buy an A style or a B style mold base. The A style mold base might be easier for the mold maker to machine but the strength of the mold base might be greatly diminished. We build all of our mold bases from scratch. We purchase the best quality pre-hardened tool steel plates, do all of the rough machining, drill all of the waterlines before we do any of the finished machining of mold base pockets, parting line lock pockets and leader pin and bushing holes. This is the only way the mold base can be exact. The mold base is the foundation and if you don't have a good foundation your mold is not going to perform well or last the life of the program.

There are a number of other small subtle ways mold makers can cut corners to achieve a lower cost. Most of these corner cutting procedure will cost the molder in terms of cycle time or longevity of the mold. As an example the design standards a mold maker uses for how they machine a sub-gate can mean the difference between a mold that stays clean during normal operation and one that always has flakes of plastic on the parting line surface causing pits and debris needing constant mold cleaning.  

One last thing to point out is what is the current economic conditions and size of the mold supplier. Smaller shops tend to be lower priced but they lack the depth to offer quicker deliveries and if there is a mistake or a change they can't always react as quickly. Smaller shops also in some cases don't have the level of engineering support in-house, which means they will cut corners getting the mold design done for less. When the economy is soft smaller shops tend to cut prices just to keep their valuable employees working. There is a big risk to have a small shop loaded with low margin work only to find out the company owner is closing his doors because his company has failed. I have seen when I requested 10 suppliers in China to bid on a new mold project and the prices ranged over 300% from low to high. The lowest price was what I had estimated it would take just for materials. Obviously I knew that was a blown quote and I could not afford to buy such a cheap tool.

Deep Mould CO.,LTD

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