The Importance of Managing Machine Shop Tools: Tips from a High-End CNC Machine Shop

06/08/2021 | Dan Karbon

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The title of this article grabbed your eye for a reason.

If machine shop tools are vital to your success, this article complements two others that may interest you. They covered choosing the right CNC machine tools for complex parts and maximizing cut tools and minimizing tool crib spending

While a future blog will likely cover specific grades and materials used to make CNC machine shop tools — carbon steel, high-speed steel, etc. — today, we’re sharing the skills needed to manage a shop full of tools.

Tool availability drives scheduling, which directly impacts the bottom line. What good is it to win a project, secure the right operators, receive the castings, and prepare a project setup cart with an incomplete set of tools needed to finish that job?

Having the financial resources to stock what’s needed on-hand, or the ability to quickly get it, is a must for modern CNC machine shops. And just as vital is the in-house capability to fully manage an entire tooling inventory.

Material Type Drives Tooling Choice

Steel. Aluminum. Gray iron. Ductile iron. The specific type of material to be machined is the single most important factor in determining the tooling and grading required to cut that material.

Here are two examples:

1) For an aluminum project involving thousands of finished parts, a wise choice may be PCD tooling (see below for more), which results in faster machining tooling, more surface footage, yet has a higher cost than our next option. A carbide tool is a cheaper alternative that performs the same cutting. The PCD tool has a higher initial cost (up to 3 times that of carbide), can cut faster which reduces cycle times, and when implemented correctly can yield approximately 10 times the tool life, saving more money in the long run.

If the quantity for that same aluminum project drops to, let’s say ... 250 total, PCD’s high cost won’t result in enough return to make the pricier purchase worthwhile. However, if the finished surface needs to look pristine, the PCD tool suddenly becomes worth the price because of its high-quality performance.

2) In another example, for a sand casting, a carbide insert could be used to perform the roughing (to open up the scale), followed by a PCD insert to do the finishing. Several steps may be the most efficient way to machine a part, again, depending on the material.

 

PCD stands for polycrystalline diamond, which are brazed tipped end mills that require robust tooling setups and high spindle speeds. A PCD could last as long as one year, depending on the cutting task; a roughing insert may last half as long as a finishing insert because more material is being removed.

 

What’s a face mill? What’s an insert? What’s a cutter body?

A face mill is a customizable tool made up of a body and inserts. A face mill body holds cutting inserts and it can be used on any job in a CNC machine shop if it’s outfitted with the right inserts. The inserts are called “perishable” because they wear down over time.

The insert, what actually cuts the metal, is placed into a pocket on the cutter body. The cutter body holds the insert so it can perform properly (cut the material and/or create the features in the part). Unlike the insert, choosing a cutter body doesn’t depend on the material being cut (aluminum, iron, steel); the cutter body can be the same for all materials, but the insert cannot.

Obviously, the perishable inserts need to be stocked, but are backup cutter bodies needed? For the most frequently used ones, yes. In a large, high-end CNC machine shop, it’s not uncommon to have 10 or more of the same cutter body. When cutter bodies wear out or get damaged, they can be rebuilt by the manufacturer, which welds the pocket and remachines it to ISO standards. Many CNC machine shops understand that the quality and performance of a rebuilt cutting body may not equal that of a new tool, and may instead choose to invest in new tooling.

Inserts are not machine-specific, but they are material-specific. What if a shop would run an insert meant for iron-on an aluminum piece? The heat generated by the insert could be enough to adhere the aluminum’s coating to the base of the insert.

CNC machine shops can implement regular maintenance to uphold high-quality tooling. One example is the often overlooked insert screws, which hold the inserts in place on the cutter body. As inserts get worn and replaced, a new set of screws should be used every third insert change. This prevents stretching the screw out, which can cause the screw to pop out and damage the cutter body. 

More Tools, Better Precision, More Success

There’s no contest. Tooling makes a huge difference. It may not be the only difference — accurate programming, vendor relationships, and inventory management all elevate a shop’s performance — but having so much reliable tooling on-hand (or quickly available) separates larger CNC shops from smaller ones. For instance, a mom-and-pop machine shop likely won’t have five different kinds of 3” face mills available at all times.

However, when comparing large shop to large shop, many basic tools are similar. It’s the custom, combo tools (multiple features that save cycle time, reduce tool changes, etc.) that separate these two. Challenging projects dictate what tools are needed, and some CNC shops search out complex projects to sharpen their skills and expand their tooling expertise.

Larger shops have the confidence to approach new projects with a singular focus: tooling their jobs up only once. It’s a plan to maximize top-end tooling and drive ultimate efficiency to give customers the biggest bang for their buck. By not cutting corners, these CNC shops can spec the best cutting tools and create the most reliable workholding.

Production Planning

Like any production process, it takes planning to prepare to machine a casting. In a CNC machine shop, covering the details makes for smooth production: the right machine, machine capacity, operator capacity, the right tooling (face mills, inserts, cutter bodies) and, of course, the castings.

Managers of the shop’s tool crib distribute a list of upcoming jobs internally. Some are recurring projects with tooling already set up and ready to go. Even a job requiring multiple tools may remain set up and stored on racks or carts in the tool crib until that set of tools is again needed.

When a new project requires setup, a list of tools is assembled at least 48 hours in advance. It’s vital to be ready when the specified CNC machine is open to run the parts. If during the setup process it’s found that a specific tool isn’t available, the tool team has three options: substitute an equal replacement tool, acquire a new tool (making that 48-hour window even more important), or shift the production timeline.

Experienced and established CNC machine shops have large tool cribs that make finding substitute tools (usually inserts) more likely.

The Necessity of a Tool Management System

With hundreds of tools being actively used, awaiting projects, or stored in the tool crib, it’s easy to understand why an effective tool management system is a must. With a click, a team member can see how many of a specific tool are currently running, in inventory, on order, being resharpened, waiting to be torn down, and ready to be included in a setup.

The most comprehensive systems go beyond inventory, they show impressions — exactly how many parts a particular drill has run for a job on a machine. Also, if a tool quantity drops under a preset minimum, the system automatically kicks in and reorders that tool on its own.

At Stecker Machine, we use the Plex Smart Manufacturing Platform, which provides the visibility and control we need to have 100% control of all aspects of tooling. 

Ready for more? See how Stecker Machine approaches CNC tooling — what tool is needed, when to invest in tools, how to implement new tooling solutions, how to build vendor partnerships — are all covered in this guide: CNC Tooling Improvements and Partnerships: A Guide to Solving Specific Tooling Issues.

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Dan Karbon

About the Author

Dan makes sure machines at Stecker Machine run fast. He optimizes cutting tools and programs for peak efficiency, corrects any manufacturing issues, and designs and selects advanced tooling for new jobs and product improvements. Starting his career in a tool and die shop, Dan joined SMC when CNC manufacturing was just taking off. At SMC, he advanced from Machine Operator to Continuous Improvement Engineer, implementing improvements that have saved approximately $500,000 over the last few years.

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