Considerations for Purchasing Your First Machining Center

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Like many who are first getting into CNC machining, I spent all my time looking at costs and very little on anything else. I did not have a lot of people to help mentor my purchases, and I kept thinking that if I made the wrong decision, my company’s existence would come to a quick end. As the years and dollars went by, I began to get a clear idea of the direction that I wanted to go with my CNC machining center purchases.

I truly believe that if your shop is a normal job shop looking to purchase a machining center, you should focus on acquiring a five-axis CNC machining center and have at least one of them in your shop. The reason I say this is that all the drawings that I am sent these days have geometric tolerancing on them, meaning the features on the drawing have tolerances relating to each other. The five-axis machines of today are built to hold these tolerances accurately without having to do the many setups that are required with a normal three-axis CNC machining center. I believe that the more setups required to make a milled part, the greater the probability of making a mistake. With five-axis, you can do a complete part in two setups and sometimes less. This is critical and if you look around, many of the successful shops have five-axis CNC machining centers.

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One of the pushbacks that I hear a lot is that it is difficult to program five-axis machines. I think many companies confuse the types of programming that can be done with five-axis machines. One of them is full five-axis contouring, which can be difficult to program but is helped by new software solutions. Another is 3+2-axis programming, where you use the five-axis machine to reorient or index the part so you can machine the features into five sides of the part. This is much easier, and in many cases it is the majority of the work that machine shops do.

I believe that buying a five-axis machine should be a higher priority than purchasing a vertical machining center and an indexer. Yes, the three-axis and indexer will be cheaper, but in the end, they are not as flexible as a built-in five-axis machining center. The indexers, in my experience, always seem to get in the way when it comes to effectively machining full five-axis parts. More often, you will have some kind of interference when it comes to indexers. They can be more difficult to set up if you take them on and off, and more setups could increase the likelihood of costly mistakes.

The other issue I encounter is that there are five-axis machines in the market where the milling head indexes. On larger machines, this should be the option since an indexing table can be too large, cumbersome and expensive to make. I find on smaller machines that the most rigid set up is where the table is doing the indexing. This is especially true when it comes to bumps. It seems it is easier to align the indexing table than an indexing head. Bumps will happen, and it is important to consider this when buying a five-axis machining center.

As I stated at the beginning, there is always the issue of price. Five-axis machines used to be very costly in the past and out of reach for many machine shops. Today, there are many five-axis machines that are more cost-effective. It is important to evaluate each machine that is available to you, and to be mindful of the support as well as service and availability. Do not compromise when it comes to price, since the future of your shop may be at stake.

If someone had given me this advice many years ago, it would have gotten me further in a shorter period of time and with less costs overall. When considering buying a CNC machining center, it is best to think of five-axis first, since it will be cheaper in the long run and make your machine shop more effective and competitive in the marketplace.