The Hidden Costs of Tooling

Although solid carbide tooling represents a very small cost proportion of the machining process, we’ve all heard the saying that ‘if you look after the pennies, the pounds will take care of themselves.’ The point in this article is that whilst carbide tooling can be relatively low cost, not taking care of the overall machining process can impact tool life and turn the low-cost tool into an expensive problem. 

For me, the number one error in machining is when a skilled engineer selects a cheap inferior tool holder that allows the tool to run out or pull out, which will ultimately create the failure of the cutting tool regardless of the cost or quality of the tool. A premium toolholder will pay for itself 10 times over by delivering improved tool life, surface finish, precision, reduced spindle power and general productivity.

Many brands offer the required clamping security, but I must admit, I like shrink fit systems. However, in theory, this offers less clamping force than other methods. HAIMER offer the Safe-Lock system and this is now available under licence from many mainstream cutting tool manufacturers. This system acts as a seat belt for the cutting tool, making it as secure as possible. It should be of interest in situations where you are machining parts that demand the highest level of accuracy or when tool and component failure or scrappage can prove very costly.

Available in the UK from ITC, BIG KAISER offers a high-performance no-slip, anti-pullout milling chuck for use with Weldon flat milling cutters. The MEGA Perfect Grip can utilise the flat on the end mill with a ‘slide in’ insert that essentially rotates with a keyway to stop any potential pull out. In addition to this, BIG KAISER is the creator of the BBT toolholding system that is now licensed to more than 170 machine tool manufacturers. When working in tandem with a BBT machine spindle, the BIG KAISER BBT tool holders are genuine face and taper toolholders that maximise rigidity, performance and subsequently tool life.

My next recommendation is the tool setting process. This can take place off line on a pre-setter or on the machine using in-cycle tool measurement. Both systems have pros and cons, but that topic is for another day.

I am going to presume that you have found the correct cutting tool for the job and selected the recommended feeds and speeds, but other simple things to consider are rolling on and off the job, especially in difficult to machine materials. Opting for climb milling where the cutter rotates in the same direction as the feed direction throws the chips behind the cutting tool and displaces the heat into the chip, rather than the cutting tool. This is especially true for machining heat resistant alloys where tool life can be reduced by up to 50- 90%, if cutting pre-machined chips.

Coolant is another huge factor that can be overlooked for its contribution to the overall machining process. It genuinely is an essential element and one we should all pay attention to. Did you know that 4% tramp oil in your machine sump will reduce tool life by an average of 18%. On an exponential curve, 8% tramp oil will reduce tool life by upwards of 28%. If you are applying expensive cutting tools or machining series runs, the downtime and costs of tooling can be a prohibitive factor in generating profits. 

I recently meet Richard Wells, Managing Director of Lubriserv and he stated that:  “tramp oil and solid particles in coolants can cause increased tool wear, quality problems during later processing and health problems for your personnel.”

In short, it’s well worth the effort to take steps to keep your coolants clean.

Like other good cutting fluid suppliers, Lubriserv offer a number of different solutions for the removal of tramp oil. This can range from a simple tramp oil skimmer, right up to the ALFIE 500. The ALFIE 500 system removes particles down to just 1 micron, reducing tramp oil from the coolant down to a percentage of less than 0.5%. It uses high speed centripetal force to remove tramp oils, grease and solids such as metal fines from cutting fluids and coolants. In other words, it removes all of the contaminants that can cause dermatitis or other skin irritations.

Another solution is the Tramp Oil Separator from Freddy Products. This is an oil separator that is easily manoeuvrable, so it can be used throughout the factory workshop. Like the previously mentioned ALFIE, it runs continuously whilst the machine tool is in operation, not to interfere with production.

In previous features, I have discussed high performance milling strategies. Believe it or not, by considering these parameters that are external to the cutting tool, tool life can be significantly increased. 

Vibration and workholding are the final points I wish to mention, as this again is often overlooked when trying to increase tool life. From a tool security perspective, I have already mentioned the BIG KAISER and Haimer systems but workpiece security is just as critical. Make sure the workpiece is being held securely and free of vibration, as this is a sure way to reduce tool life or even break the tool. This is also true on a turning centre. Make sure the part is secure in the chuck prior to any machining taking place from the Y-axis or milling function. Secure clamping in turning is susceptible to reduced clamping forces as the chuck speed increases, but this is a topic for another day. I hope this features helps and if you require anything further, feel free to get in touch via social media.

This feature is from the March issue of the MTD Magazine..