Take up the challenge

Cajero’s engineers love the challenge of figuring out complex issues
Cajero’s engineers love the challenge of figuring out complex issues

When it comes to machining challenging composite components, you need a technical partner capable of figuring out the complex issues. According to Cajero’s CEO, Alex Harding, the company never lets a challenge pass it by.


The desire to increase energy efficiency and reduce component weight is a major driving factor in the development of new products and has led to the widespread adoption of carbon fibre-reinforced plastics (CFRP) and combinations of CFRP and metal. However, whilst they combine excellent mechanical characteristics, they are equally challenging to machine accurately and efficiently.

From its 15,000ft2 facility in Queenborough, Kent, Cajero designs and manufactures a range of standard and engineered cutting tool solutions for the civil and defence aerospace supply chain. Customer productivity gains and product innovation are at the core of everything it does. A family-owned business, Cajero says it provides an unwavering commitment to the development of its high-performance solid carbide and PCD cutting tools for customers machining products made from an ever-changing mix of composite materials.

Q) Firstly, please provide some news on your latest tooling product launches?

There’s always a lot going on at Cajero. FIBROSINK one-shot drilling and countersinking composite stack components feature heavily. An added upshot from the work is a standardised drill for CFRP and titanium stack components demanded by many customers.

Alex Harding, CEO of Cajero
Alex Harding, CEO of Cajero

Cajero’s FIBROCORE Series has been expanded to include the QuickLoad system. Customers can now retain the precision adaptor in their shrink-fit toolholder when they’re exchanging worn knives and munchers for new. The adaptors also come in an array of shank diameters as standard to handle the vast variety of toolholders.

The FIBROMILL Super Carbon Router (SCR1) refines Cajero’s serrated diamond coated router even further, quickly becoming a first choice for many. The SCR1 family comes in helical, straight, downward, and ballnose variants, from 3mm diameter to a 20mm monster.

Q) What are the types of performance demands placed on your company by today’s customers?

The great exodus of skilled, talented and time-served engineers from the industry leaves an enormous capability shortfall that’s hard to replace. But, if you’re able to dovetail into your customer’s business, standing shoulder to shoulder with their teams to quickly figure out tough machining problems, then there are many opportunities to grow together.

Q) And, how much customer hand-holding is involved in your tool sales process?

Before entering any new project, we work together on setting goals, timelines and expected outcomes - without it you have chaos. With many clients running 24/7, setting time aside for test and evaluation can be tricky, resulting in legacy tooling being prevalent and the latest advances not being enjoyed. A simple way to overcome this is pre-validation trials at Cajero HQ. Coupons of customer material are shipped over and undergo a six-step system of testing and evaluation.

The details aren’t important; the key point is our customer gets a set of images, video, machining data, process information, and recommended tooling. All of this is then validated at their site, with Cajero typically being on hand throughout. When customer capacity allows, the entire process can take them forward quickly – without the usual hassle. During the last two years, Cajero opened up the service following customer requests to include cutting tools from other global leaders. So far this is working well.

Q) Why are specialised composite cutting tools needed for composites as opposed to using traditional metal cutting tools?

Like many workpiece materials, specialised cutting tools are required, and composites are no different. Even within the composites machining space, no one size fits all. Cajero has developed 11 drill variants for this reason.

Cajero designs and manufactures a range of cutting tool solutions
Cajero designs and manufactures a range of cutting tool solutions

If you’re drilling carbon composites, then 8-facet ‘double angle’ geometries can work well. But if the exit face has an additional material layer – with Tedlar for example - then a special 4-facet drill point geometry may be preferred. If you consider Kevlar, with its typically low resin to fibre ratio, it dislikes centre-cutting drill points, as they tend to push or deflect the material. In this instance, specialist trepanning drills should be considered, and I don’t mean basic w-point drills.

Trimming and slotting operations have similar challenges: splintering, delamination, fibre pull-out issues are the bane of the machinist. Helical flute, straight flute, downward pushing flutes, compression flutes, scissor action or pre-tensioning designs all have their place. Cajero has developed 13 router variants for this reason.

Q) What elements of composite drilling need to be considered for any typical job and how do they differ to metallic drilling?

Whenever you’re optimising a job, it’s important to view the whole - in other words, take a holistic view. It’s easy to make the cutting tool the villain if the expected outcomes are not being met. But that’s not the end of the story, it’s just the beginning.

Of course, ensuring adequate swarf/dust removal is a priority, either by powerful extraction systems or sufficient clearance under the machined feature, so that it can drop away. Without it, recutting circulating debris causes premature tool wear and is highly likely to affect component surface quality.

Next, it’s important to check there is appropriate workpiece support, especially underneath the machined feature. Delamination, poor surface finish, out-of-round holes in the case of drilling, can all be signs of inadequate support. Then, toolholding, machine spindle runout, coolant pressure… the list goes on. Once all have been assessed and adjusted, if possible, it’s time to get the tool in the chuck and begin. But where do you start?

For Cajero, its library of proven data established during the last 30 years, is a good starting point. Even so, you don’t always get it right first time, and there are moments where you’re left scratching your head.

Q) What are the different challenges posed by different composite-related materials?

I’ve already alluded to one size not fitting all. Take some carbon composites for example, featuring ‘dry’ exit faces, meaning they have a low resin content. As we know, they can be challenging to machine cleanly, but add to that a more fibrous exit surface, then the potential for delamination is amplified.

It’s certainly possible to overcome such challenges by combining the right tool geometry and optimised machining data. Other considerations may include improving the support under the machined feature, or even adding a sacrificial backing layer to brace the composites.

Q) What kinds of technology developments do you foresee in the composites tooling arena going forward?

The great thing about the composites industry is it doesn’t stand still. One trend we’re seeing is greater demand for sophisticated modular tools that are both cost-effective and simple to use. By combining precision adaptors with replaceable wear part technology, the worn drill or insert is simply swapped out for new – rather than throwing the entire tool in the scrap bin, or getting it reserviced a couple of times at a high cost.

Cajero’s OSI Series CNC drill countersink system
Cajero’s OSI Series CNC drill countersink system

Take Cajero’s OSI Series CNC Drill Countersink System for example. Not only do you control your costs by only exchanging the used tooling, you get another massive win when using it in one-way assembly processes that combine multiple operations into one, i.e., drilling, countersinking, radius, spot facing.

Q) What are your thoughts on Industry 4.0 and the factory of the future?

Many of Cajero’s aerospace clients (ourselves too) are adopting Industry 4.0 technologies and practices to stay ahead. Seeing data on machine utilisation, robot activity, and assembly line processes, in real-time, enables informed decisions to be made fast. Yet, some of the greatest benefits of the future factory will be for its people, with automation and cobots removing the dull, dirty and dangerous tasks associated with a process.

Q) What do you feel are the most important assets of a company?

In our experience, placing the customers point-of-view at the heart of how you act is one of the most important ‘assets’ of your company. Customers don’t care about your strategy, people, products or technology – they care about what you can do for them. That’s not to say those things aren’t important to you, but they’re there to serve and answer your customers challenges as seamlessly as possible.

Q) Broadly speaking, what differentiates your company from the competition?

Cajero remains focused on becoming the essential cutting tool partner for in-house optimisation teams seeking to improve their machining productivity of complex parts. Put simply, industry leaders choose Cajero for our ability to solve difficult technical challenges fast.

Q) Would you say that your long-standing partnerships have brought huge benefits?

With 83% of Cajero’s ongoing business coming from 20+ year partnerships, you get to know each other well. What works, what doesn’t, expectations and future aspirations. By working alongside your partner, rolling up your sleeves and getting stuck in, well, that’s when the magic happens. When teams integrate and collaborate on the big issues - and the trust is absolute - it’s difficult to see where one company ends and the other begins.

Q) Finally, where to next for your company?

We will continue developing partnerships with aspirational growth companies around the world by expanding our Grow Together Programme (GTP). GTP provides customers with proven manufacturing strategies, real-life machining tactics and practical cost-out tips that enable them to skip the guesswork and accelerate their productivity. We want to become known as the most ‘can do’, capable and caring cutting tool partner in the world. To do that, we only want to work with the best. The future looks bright.

As a lasting legacy, Alex Harding is on a mission to get more youngsters to train as engineers. Follow this link to his LinkedIn profile featuring the piece: https://bit.ly/3JfaIxc




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