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Palletizing for automation

Palletizing for automation

If workpiece setup is basically a simple, yet not easy, process in manual operation of cnc machines, it can become much more complex in automation, and if palletization is often an obvious answer, making it an operational reality is not so straightforward.

The concept of automating cnc machines is very charming but , as all very attractive things they sound often too good to be true. When speaking with colleagues about automated operations in a cnc workcell, although this captures their interest a lot, I often see a certain amount of fear in their eyes, that probably everyone who has even a small amount of experience with machining can understand.

Chips are not a big concern in a system designed for automation

Leaving a cnc machine making chips alone, unmanned, can be unacceptable for most people, and for me as well for a long time. Taking care of a machining job is the first worry of a earnest machinist. Attentive and painstaking care, deburring, fitting, and fine tuning of machining are the heritage of an old school that I really miss (link to sip 1h), but how about the future? Steam trains where at the edge of technology one century ago, but today nobody would seriously travel with them if not for a romantic revival.

One of the basic concepts in workshop development should be scalability, or the capability of a system to be continually upgraded without the need of replacing nearly anything but only adding what is required by a process improvement or a resource increase. Automation perfectly matches this principle, for this reason placing the right foundation is vital to avoid later impasse in growing.

With this in mind I’ve always been worried about choosing a palletising system that could be easily implemented and extended to fulfil all subsequent needs.
Choice considerations are many, but probably the mother of all them is cost. Palletizing systems are expensive, but , to really get advantages from them, you must have plenty! Running out of pallets in the middle of a job, its really like driving a formula one car with a flat tire. So I always thought of a system that could be easily expanded also by manufacturing many of its parts in house.

The very first step into automation basically requires elimination of setup time, it has to be assumed that putting a workpiece on a machine tool ready for machining has to be done in a few seconds with a simple operation, accurately and with total reliability.

Mold manufacturing today is very much like fighting a battle and having the most modern weapons really makes a difference, and the biggest difference comes from the ability of feeding the machines with a continuous flux of jobs.

Manual pallet bases to be fitted to a bigger automated pallet.

A good pallet system ensures a repeatability of less than 0.003 mm, that should be retained throughout its lifecycle.
Personal experience, after some years, tells me that a good concept for a pallet mating system is one where reference surfaces are pretty extended and well protected from coolant and chips.

Also the number of mating faces is relevant.

Theoretically a pallet clamping system has to have one reference for locating zero point according to x y z axes and a second one to fix rotation on c axis, but I have found that, although four clamping posts all with centering features may seem redundant, this increases a lot overall reliability and accuracy over time (assumed that their placement is very accurate). I have heard of pallet receivers with one or two broken reference mating surfaces without any loss in positional accuracy and rigidity .

A reliable and robust pallet system is a solid base upon which developing all workpiece setups regardless of the type, once the pallet system is well established, a whole new world of opportunities is behind the corner for creating a totally flexible manufacturing system.