Any injection mold manufacturer can quote a low price mold, but it takes a committed partner who is familiar with your company and processes to engineer the lowest cost solution. That means an up-front investment in time and expertise which only comes out of strong working relationship.
I find that it’s better to invest time to get to know one or several injection mold producers really well. Visiting them is best and once you get a good feeling about it (after discussions or making a small test mold), the future will be a lot easier. I have a good relationship with an injection mold manufacturer and because we know how we think about the technologies, we work faster and more effective towards the objective. That’s where the profit is along the life of the project. Metal is metal and CNC machines are the same for everyone. In the end it comes down to people and if someone does a value stream analysis of a project, the mold quality is often not considered, whereas it actually determines a lot, as you know.
The best practice is to avoid preparing the Excel sheet containing 3 to 4 different mold makers quote and make a rating based on the price. Visit the mold maker plant and check the facility available with him, his existing customers, past customers. Check the molds which are under manufacturing in the shop, see the procedures followed, look at the sample components made from the molds supplied by the mold maker. All this will give you an idea on the capability and the quality levels of the mold maker.
Then check which is your most important requirement like, time of sample submission, finish of the part, dimensional criticality, quality of steel, after sales service like modification of mold based on the change in part design during the life, serviceability of the injection mold during the production in your factory etc.
Don’t make rating only on the quoted price, no doubt it is very important but not the only important point. More important don’t allow the final decision to pure commercial man, involve a technical person from the start.