9 Essential Factors to Evaluate Before Purchasing a Vertical Knee Mill

Knee mills are precision machine tools engineered to create high-end components. Purchasing such a machine requires careful consideration of a number of questions, including what kind of knee mill to buy, and what parts and service support to look for. 

How does a knee mill function? 

A knee mill is a type of vertical milling machine, used to perform a wide variety of milling processes such as cutting, surfacing, slotting, and drilling. Often referred to as a vertical knee mill, the workpiece is clamped to a table mounted on the knee that moves horizontally along the X and Y axes. A quill allows the cutting tool to achieve a certain range of Z-axis motion. High RPM milling tools spin to make precise cuts to the workpiece.

Vertical knee mills provide a wide range of motion for cutting, offering the ability to work in a wide range of machine shops from individually owned machine shops to large manufacturing operations. CNC knee mills are less common, but provide a powerful control system and appeal to a variety of experience levels. 

What should I consider when buying a knee mill?

Cost

A vertical knee mill itself is generally a big investment. Whether you’re buying a new or used machine, there are other costs that you need to consider. For example:

Transport: moving equipment would incur transportation expenses. It’s a good idea to carefully consider your business needs and growth before purchasing a vertical knee mill. Smart purchasing decisions such as shipping consolidation and warehousing services can help to reduce expensive travel costs.

Replacement parts: since vertical knee mills are often used for extended hours at high speeds, wear and tear are a part of the process. 

Add-ons: if the machine you’ve purchased is bare bones, there might be some attachments you’d like to install based on the products you’re going to fabricate. Consider accessories and installment fees. 

Size

If space is a concern for you and you plan to work with materials that have a lower hardness, buying a vertical knee mill with a compact footprint will suit smaller workspaces and machine shops. It will also be easier to transport, ultimately saving additional costs. 

Compact machines today offer a much smaller footprint with a great deal of accuracy and quality finish depending on the material you’re working with. It is important to think about your requirements from the machine in terms of what you plan to produce. Large size machines tend to offer more stability especially when machining hard materials such as steel. Better stability means the machine will not flex too much when applying the force required for the part. Using a smaller machine for complex materials can result in vibrations that reduce the accuracy and achievable tolerances.

Production volume

A commercial quality mill is often enough for low to medium production volume. Industrial-grade vertical knee mills are a better choice for mass production that involves hours of continuous complex machining. 

Speed

A higher spindle speed adds cost and may not always deliver the best accuracy. Research and determine what the required speed range is for the parts you will machine and look for those speeds when shortlisting your options. 

Tolerances

If you’re new to machining, you need to know about machine tolerances. Machine tolerance indicates the level of precision required to produce a part. A smaller or “tight” tolerance means you need more precision. On the other hand, a larger or “loose” tolerance signifies a lower precision requirement. Machines with tight tolerances are also more expensive because of the wear that occurs when a tool produces multiple versions of the same part. Understanding precision and tolerances will also give you more insight to the longevity of different machines. 

Tooling and workpieces

When purchasing your vertical knee mill, make sure that the configuration and cost reflect all the tools and workpieces that you require such as vice, drill chucks, and more.  

Materials

What materials are you machining on your vertical knee mill? Each material has its own unique characteristics, and therefore a different level of achievable tolerance. Hardness, abrasiveness, and heat stability are some of the characteristics that come with materials. Your choice of a knee mill should consider a machine that suits the materials you plan to work with. 

Programming and control

For new machinists, the best choice is a vertical knee mill that offers easy-to-use controls. Conversational programming is a great start as it allows easy operation when generating programs on the machine’s control. Built-in data prompts guide operators who can select the right dynamics for the machine process. 

A great example is the Smartcut EVS CNC Vertical Mill from Summit which features a Fagor 8055i MC control system with a powerful ISO G-code control and Icon programming. Complex machining tasks are easy to program with highly interactive graphics, making it a great fit for operators of any experience level!

Service and Support

When deciding on the right vertical knee mill machine, it’s important to consider the support you need to ensure sufficient maintenance. Just like any other machine, a vertical knee mill requires cleaning and regular maintenance for quality control. Here are some things to consider: 

• Do you have access to quick service? 
• Are there any technical service centers near your location? 
• How much will you have to pay for repairs and spare parts?  

Purchasing a knee mill from Summit Machine Tool ensures that your knee mill arrives fully assembled, fully calibrated, and with clear instructions for use. Additionally, our service department is here to help, so contact us if you run into any questions. Our speedy parts and service department ensures that spares are sent out as quickly as possible. 

Conclusion

Before buying a knee mill, be sure to prepare and research. Your budget should reflect the quality, cost, features, specifications, tooling requirements, and longevity required of the vertical knee mill. If you’re not tech savvy or don’t have the expertise for installation, be sure to check for the price of having a professional installation done for you. 

Summit Machine Tool offers complete solutions for high quality equipment, support, and parts and service to assist you with your vertical knee mill requirements.