Choosing the Right CNC Machine for Your Shop

Production can grow from a garage machine shop to an industrial space in a short time with finding your niche and booking a few key orders. If you are moving from manual machining to CNC machining or increasing the number of CNC machines you need to consider factors like skilled labour, storage, and a host of other things separate from the machine, itself, to set up a solid plan for operations to serve you now and move you into the future. Choosing the right CNC machine for your shop, however, is the key factor with a variety of considerations including cost, production needs, and machine specifications.

Machine Considerations

The investment in a new CNC machine is substantial so getting the longest life is a major consideration. Lifespan can be affected by several factors. The weight of the machine, for example, for tough cutting jobs is critical. Cast iron is a solid choice for durability. Life is also determined by maintenance, cutting speed, lubricants, and other operational choices. These maintenance factors are affected by a few key components.

Tool Repair and Replacement – When researching your new machine check for lead time on parts as well as cost and availability of cutting tools for replacement needs. Keeping a small inventory is generally helpful to keep production running.

Downtime – Keeping parts on hand is essential to avoid downtime, but there are always unexpected breakdowns. Work with a trusted partner who has knowledgeable phone support as well as quick in-person service when needed.

Speed – Both spindle speed and cutting speed offer a large spectrum of choice. Using these incorrectly can cause damage. Onsite training with purchase is offered by quality machine suppliers and this should be taken full advantage of.

Other considerations on machine choice include practical selections based on size and task.

Power Consumption – Check machine specifications to assess if you may need an increased power supply in your shop. The cost of a one-time upgrade, plus the monthly hydro rate should be weighed against the cost of the equipment compared to one with a lower power draw.

Worktable – Consider a working radius larger than your biggest part. This doesn’t limit new projects and keeps logistics of part production to a minimum with the excess area.

Machine size – Vertical machines take up less floor space than horizontal tables. The size of the cutting bed is important to the work you do, but machine size is a factor based on floor space. Sizing also needs to take into consideration the supporting gear needed to run the machine, any water or air-cooling systems, and raw material storage.

Specifications – Speed, material choice, and tolerances all establish the specifications of your new machine choice. If CNC machines are new to you, be sure to get a variety of inputs and work with a trusted source to determine stroke range, number of axes, spindle motor power, feed rate, and maximum tool length. These all determine the accuracy and speed at which you can perform tasks over the life of the machine.

Production Considerations

If your production consists mostly of simple cuts, the simplest machine for the job may be the best way to start. The risk is the least but consider your timeline for expansion and weigh the costs and benefits of simplicity versus readiness for leveling up. This same approach applies to the CNC machine centre. The choice of approach should be based on the main performance of the machine. Vertical, horizontal, as well as the number of axes for the machine centre change the approach to milling operations. The main machine performance also needs to consider these factors:

Tool Changes – The most effective production utilizes the least amount of tool changes. Use the skills of a quality machinist to determine the approach to manufacturing with the least changes. A more costly machine with multiple axes will require infrequent tool changes compared to fewer axes and re-setting the workpiece for different approaches. Many high-speed machines can provide both forming and finishing with the same tool.

Precision – Part design with sharper corners, angles, or high-quality finish will require a machine that runs at higher spindle speed on multiple axes. The precision tolerances of your parts will determine the quality of machine you may need to purchase to provide the appropriate quality efficiently.

Cutting Approach – Vertical and horizontal cutting each have their benefits. As noted above, vertical machines take up less shop floor space. They also have the ability to manufacture pockets easier so offer a good choice for custom shapes and holes. A horizontal machine, on the other hand, uses its 4th axis around 60% more than a vertical machine, resulting in faster production.

Financial Considerations

Debt must always be balanced against production and cash reserves. We provide financial insight for overall operations in a separate article. When it’s time to buy equipment, consideration of used equipment may be more attractive than new based on your finances. Some considerations for used equipment will be higher maintenance costs and a shorter lifespan. These factors for assessing the value of used equipment will help in your purchase.

Machine Hours – The total machine hours is one of the first considerations in buying used equipment. There is a difference between hours in operation and actual cutting hours, with cutting hours being the most important. A supplier should be able to provide you with the machine hour rate also. This number is a calculation of the expense of running the machine divided by the number of hours the machine was in operation during a set time.

Paperwork – Gather as much documentation as possible including repair history, bills, and manuals. If production logs are available this shows details like setup time and downtime due to repair. The more data you have the more informed your buying decision will be.  

Trusted Dealer – The final detail in purchasing used equipment is to be sure you are working with a trusted CNC dealer. Get referrals from other shops to be sure ethics and level of service are high. Also, ensure the machine manufacturer is still in business and parts are readily available.

There are many considerations in purchasing a new CNC machine. It can be tempting to jump at a good price or buy machines from a shop that is closing to expand your business. A focus on your current production needs and future goals is most important to acquire the right machines. Choosing the right CNC machine for your shop encompasses a detailed look at price and specifications, but the type of production, current space available, and future expansion plans are also necessary to make a sound investment.