The DeHoff 20144 is used to perform gundrilling, pull boring, roller burnishing, and thread tapping on the aluminum microwave guides. The microwave guides are long tubes used to heat the plasma fluid inside the Tokamak vacuum chamber to 150 million degrees Celsius, which are the conditions needed for nuclear fusion.

The DeHoff 20144 has a gundrilling diameter capacity of 2 inches (50.8 mm) and a maximum drilling depth of 144 inches (3658 mm). It features custom workpiece fixturing and tooling to perform the gundrilling, pull boring, roller burnishing, and thread tapping operations all on a single machine. DeHoff gundrilling machines are designed and manufactured by Kays Engineering in Marshall, Missouri, USA.

Teledyne Brown Engineering, as the prime on a contract to supply US-ITER, based at Oak Ridge National Laboratory, has ordered the DeHoff 20144 to fabricate waveguides for the ITER reactor which will be located in Cadarache, France.

“Hommel Präzision is a well-respected, customer-focused organization and we are happy to have them as an official part of Sunnen,” said Chris Miltenberger, President, and CEO of Sunnen. “Our customer base benefits directly from the in-country sales and technical support capabilities.”

Honing has proven itself for decades as an alternative to internal grinding, fine turning, reaming and roller burnishing. Through its decades-long affiliation with Hommel Präzision, Sunnen is an established leader in Germany for honing components for the metalworking industry. And, as a systems manufacturer, Sunnen offers all the necessary tools, fluids, gages and accessories from a single source and not just honing, but more recently, in the past few years has provided a full line of deep hole drilling solutions, including machinery and the cutting tools to support them.

Sunnen’s bore finishing solutions include vertical and horizontal honing machines for single and series production; automated honing machines as processing cells or multi-linked systems; single and multi-spindle, modular honing machines with maximum variability; portable hand-honing devices for complex workpieces and individual parts; and a wide range of grinding strips, honing tools, honing oils, bore gages, and tools for third-party products. Sunnen’s deep hole drilling line of products includes deep hole drilling and skiving and roller-burnishing machines, cutting tools, cutting inserts and accessories.

Sunnen’s world headquarters and main manufacturing plant is in St. Louis, Missouri, with additional sales and manufacturing facilities in 14 countries spanning the globe. Total employment is over 700 worldwide.

In industries such as aerospace, automotive, energy and food service that often machine stainless steel and HRSA materials, the cost-effectiveness and reliable performance of the M geometry insert are a necessity due to the high costs of these raw materials, which are among the highest in manufacturing. Because the use of these materials continues to grow in many industries, improved drilling solutions like the M geometry target difficult-to-machine materials—a key factor in remaining competitive in any market.

Additionally, the design elements of the T-A Pro M geometry allow larger diameters—1 inch and above—to be used on smaller or under-powered machines where additional setups on other machine tools would be needed or where parts would need to be contracted out. Machining components in-house cost-effectively while meeting specifications every time ultimately increases throughput and profitability.

John Weniger, product manager, shares that “In a material class where applications are known to bring unpredictable results, the new M geometry T-A Pro insert has been engineered to provide a winning combination of tool life, penetration rate, and process reliability so that you can feel confident when applying the tool to your specific needs. The addition of the M geometry solidifies the T-A Pro line as a comprehensive, industry leading solution when it comes to holemaking.”

About Allied Machine & Engineering

Allied Machine & Engineering is a leading manufacturer of holemaking and finishing tooling systems. Allied devotes its advanced engineering and manufacturing capabilities to creating the widest selection of value-added tooling available to metal-cutting industries around the world. Our tooling solutions deliver the lowest cost per hole in a wide range of drilling, reaming, threading, boring, and burnishing applications.
Located in Dover, Ohio, Allied’s precision holemaking technologies provide end users worldwide with the highest level of drill performance. Precision engineering and expert application support make Allied the first and best choice for solving complex metal-cutting challenges.

Chip Formation: Shape & Size

When looking at chip formation, a key indicator of a good chip is the shape. The preferred outcome for any application is chips shaped as sixes and nines or a single conical shape. These small, manageable chips are essential for efficient, predictable drilling. Nevertheless, it is important to be aware of what chips in other shapes and sizes can indicate. For example, a straight, flat chip is a result of elasticity. If the chip is a continuous ribbon, then there are likely many adjustments that need to be made in order to achieve ideal chips.

The size of the chips impacts evacuation as well. There are two major factors that impact the size of chips in drilling tools: chip breakers, also known as chip splitters, and lip geometry. With chip breakers, the width of the chip is thinned to allow for easier evacuation; the wider the chip the easier it is to get it to roll onto itself and break. Lip geometry acts as a mechanical chip breaker to fracture a chip by curling the chip on top of itself or by impacting the chip forming with the backside of the lip radius. Although harder materials will curl a chip on top of itself to create chip fracture, gummier materials often skip over the lip radius and only fracture after impacting the back of the lip radius. Still, the purpose of the combined chip breakers and positive lip geometry is to break off the chip so that it is narrow enough to easily evacuate.

Chip fracturing can also occur naturally due to the velocity differential between the outside and inside of a chip, which creates a cone-shaped chip that curls on itself and fractures. Because larger diameter inserts have a higher velocity differential than smaller diameter inserts, it is easier to fracture chips i.e., the larger the chip breaker spacing the more chip fracturing that will occur. Smaller diameter inserts are limited to the velocity differential available due to the restriction on the chip width required to easily evacuate chips through the holder gullet.

Thickness

The thickness of the chip varies with the feed rate; heavier feed rates form thicker chips while lighter feed rates form thinner chips. The thickness of the chip formed decides how the chip will fracture, but this is also dependent on the material being machined. At the same time, changing the speed impacts the chip thickness; the higher the speed of the tool, the more heat generated in the cut, which makes the material more elastic. So a balance between speeds and feeds is necessary. With many materials, a thicker chip means there is a greater chance of exceeding the elastic limit of the materials, which increases the likelihood of chip fracture; on the other hand, thinner chips are more elastic and, thus, farther away from the elastic limit necessary to fracture the chip.

Soft, gummy materials like soft carbon steels, 300 series stainless steel or pure titanium have a high elastic limit—so much so that increasing chip thickness has a negative effect on chip formation. Materials like these require specific lip geometries to potentially create an acceptable chip. Nevertheless, it is key to look at the chip deformation ratio of materials to better understand chip thickness. The chip deformation ratio can be defined as the ratio of deformed chip thickness over the undeformed chip thickness (feed rate). For most steels, this ratio is typically 2-3:1; however, it can be as high as 5-10:1 for those soft, gummy materials. Ultimately, though, this measurement is an indicator of chip form and elasticity in the material being cut, and the higher the deformation, the more difficult chip formation will be.

Coolant

When it comes to coolant, through-tool coolant when paired with the right drill geometry is critical for the best chip formation and evacuation. Additionally, changing coolant type, pressure and volume influence the thermal shocking of chips. This can change the properties of the chips and make them more or less likely to break into manageable segments. For example, coolants can decrease material elasticity due to the strain hardening that occurs as coolant quickly cools hot, elastic chips. The cooling of elastic, continuous chip formation embrittles chips to the point of fracture by reducing their elastic limit.

For chip evacuation, coolant pressure and volume are important. To evacuate a set volume of chips, a set amount of kinetic energy is provided by the coolant volume. Drilling can occur uninterrupted from the top of the hole to the bottom as long as enough coolant volume is available, which will be evident during the application with a steady load meter reading while drilling. With an insufficient coolant volume, an unsteady load meter will be detected when drilling into the hole. Although this does not mean that drilling with insufficient coolant is not possible, it does demonstrate that the drill must be altered to fit the environment.

Pressure on the other hand is the force behind the coolant that provides a fixed volume of coolant through a given diameter. As coolant pressure is increased through a fixed coolant orifice diameter, the coolant volume will increase. When drilling small diameters, high coolant pressure is needed in order to provide sufficient coolant volume, but as drill diameters increase, high coolant volume becomes more necessary than high coolant pressure. In high-production drilling—especially deep hole drilling—the tool coolant is critical because it provides an upward force on the chip to aid in flushing the chips through the drill flutes and out of the hole. Although flood coolant can be used alternatively to through-tool coolant in short drilling applications under two times diameter, in deeper holes flood does not promote good heat transfer and can also push chips back into the hole, which can cause chip packing.

Through-tool coolant is also important when factoring in heat because it provides coolant right to the cutting edge where it is needed to cool the tool. When machining, 60% of the heat generated in the plastic deformation of the material remains with the chip formed while the other 40% remains with the tool and workpiece. This portion that stays with the tool must be evacuated by coolant in order to have sufficient tool life. Clearly, when more coolant pressure and volume can go through the tool, the cooler the tool will run. This then means that there will be greater tool life and that the tool can potentially be run faster.

Tool Selection

Chip formation can also indicate whether the best tool is being used. If the chip formation is not meeting the standard, a change to tool geometry may be needed in order to improve the situation. Clearly, the geometry of a cutting tool has a significant impact on the chip formed. Specifically, increases in rake angles can improve chip formation, yet this does come at a cost because the greater the rake angle the weaker the cutting edge.

Rake angle also highly influences the value of the shear plane angle, which is the angle formed by the pure plastic deformation of the workpiece material. Here, the material starts deforming or chip forming in front of the cutting edge. For both material properties and running parameters, the angle varies; however, it should always be a goal to make the shear plane angle more vertical because the steeper the shear plane the better chip formation.

Chip thickness comes into play here as well. The more elastic a material is the steeper the shear plane angle will be, resulting in a thinner chip. Conversely, the harder the material is, the flatter the shear plane angle will be, which means a thicker chip is formed. All in all, more rake angle means more shear angle, which means better chips, but balance is key here as well. A really sharp cutting edge will make great chips but will fail and break due to a smaller cutting edge cross section and weaker cutting edge, so find balance in the rake angle—one that is aggressive but not overly so.

Changes in Chip Formation

A final thing to look for when examining chips is any changes in chip formation. If chip formation is altered during an application, it could be caused by a myriad of elements: wear on the tool, built up edge on the tool (BUE) or changes in the environment like coolant or material changes. In new applications, it may be best to drill shallow test holes and take a look at the chips to make sure they are small and segmented. Being conservative in the beginning with speeds and feeds could also aid in better understanding chip formation and what adjustments need to be made.

Awareness of any changes in chip formation is key, though. Poor chip formation can cause major problems in drilling applications. Long, continuous chips are difficult to evacuate and can become packed in the drill flutes, damaging the drill or even causing drill failure. These long chips could also become wrapped around the drill body and again cause tool failure. Lastly, poor chip formation impacts the hole quality. If chips are dragging or packing in the flutes, there will be poor hole finish. Noticing any changes in chip formation is important not only for tool life and hole quality but also for the overall success of the application.

Knowing more about the chips formed in any metal cutting application enables machinists to better control the outcome and success of drilling operations. While it is necessary to examine chip size, shape and thickness, it is just as important to know how coolant, tool selection and changes in chip formation tie into the application as well. So take a look at the chips being created and break it down chip by chip because both proper chip formation and chip evacuation are required for successful high-production drilling.

About Allied Machine & Engineering

Allied Machine & Engineering is a leading manufacturer of holemaking and finishing tooling systems. Allied devotes its advanced engineering and manufacturing capabilities to creating the widest selection of value-added tooling available to metal-cutting industries around the world. Our tooling solutions deliver the lowest cost per hole in a wide range of drilling, reaming, threading, boring, and burnishing applications.

Located in Dover, Ohio, Allied’s precision holemaking technologies provide end users worldwide with the highest level of drill performance. Precision engineering and expert application support make Allied the first and best choice for solving complex metal-cutting challenges.

Previously, when machining firearms, some processes were manual or utilized numerous different tools; however, as tooling innovations have developed, the process of machining has evolved. Oftentimes, tools now are far superior to those used in previous firearm production methods. This provides the opportunity to combine operations into a single cutting tool, eliminating the need for additional tooling in the machine shop. In addition, new innovations in tooling provide manufacturers with a better output like improved surface finish or decreased cycle time. Nevertheless, there is still a need to work toward standardizing tooling in the firearm industry. While manufacturers often have their own take on the radius, angle change, etc., standardization is becoming more common. For example, a standard reamer could be used for all one-inch diameter holes in an AR upper receiver; however, there could still be a delay in acquiring the tools if specific reamers are needed because of the needs of different specs.

Holemaking and hole finishing are part of the machining process for numerous firearm components. One example of this would be revolver cylinders, which in some cases require a three-step process: pre-drill, pre ream, and finish ream. Form is critical throughout these applications because it must match the bullet casing. Other firearm components that need holemaking and hole finishing applications include AR upper receivers, gas blocks and bolt carriers, which house the firing pin and bolt itself.

In deciding what type of material to use in firearm components, manufacturers must consider a few characteristics: weight, strength and aesthetic. Take steel as an example. It is durable and versatile, making it easier to manipulate into the small parts needed within firearms, yet it is a heavier material. While this does present some challenges, it also provides better control and repeatable accuracy. Conversely, when using aluminum, strength and durability are compromised for the benefit of less weight; therefore, it is best to consider a type of aluminum alloy.

Ultimately, the materials used must be reliable because of the stress they are put under, the heavy usage, and the strict requirements of the industry itself. While firearms are often heat-treated, it is best to complete holemaking applications prior to this; after being heat-treated, the material is typically too hard for drills because it is as if machinists are asking two like materials to get along. Instead, the drill should be harder than the material you are drilling; something that is challenging to achieve.

Whether it is alloys, titaniums or another high-grade exotic material, tool life is vital in the holemaking and finishing applications. One of the key needs of manufacturing firearms is sequential, repeatable processes; thus, tool life is needed to maintain optimal production cycles. Although tool life issues like dulling or breaking can sometimes be easily resolved by switching to a different geometry or coating, there are times where greater changes need to be implemented. Chatter, for example, can cause poor tool life, so manufacturers would need to evaluate their fixturing, work holding or machine maintenance in general. Performing machine maintenance or replacing tooling ultimately impacts production time, so it is best to utilize rigid machines and high-grade materials when possible.

Surface finish is one of the most important elements when machining firearm components such as bolt carriers, upper and lower receivers, and silencers. More specifically, surface finish is key for firearm chambers because of the need to accept the incoming cartridge, which determines the accuracy of the rifle and the load being fired on target. When drilling or reaming, surface finish is critical—the smoother the surface finish the less friction and less wear. Clearly, there needs to be a smooth and consistent finish free of burrs; otherwise, this becomes a fracture point. Ultimately, surface finish impacts the functionality of the machined firearm while negatively impacting the life of the barrel as well.

At the same time, there needs to be consistent wear coming from the finishing tools and on the finished part itself so that there is no excessive friction or wear. Here, CNC operations provide the most accuracy and consistency while creating a process that can be easily replicated. Not only do manual processes produce an inconsistent surface finish, but they also are more costly to production and the well-being of the operator—both of which impact product quality. Therefore, CNC machining improves the performance and life of the firearms because of the ability to remove microscopic peaks and valleys in the material.

Machining firearms clearly requires precision and efficiency. Whether drilling or reaming, it is necessary for machine shops and manufacturers to develop a process that is repeatable, sequential and effective in producing the high standards—like that of surface finish—needed in the firearm industry.

About Allied Machine & Engineering:

Allied Machine & Engineering is a leading manufacturer of holemaking and finishing tooling systems. Allied devotes its advanced engineering and manufacturing capabilities to creating the widest selection of value-added tooling available to metal-cutting industries around the world. Our tooling solutions deliver the lowest cost per hole in a wide range of drilling, reaming, threading, boring, and burnishing applications.

Located in Dover, Ohio, Allied’s precision holemaking technologies provide end-users worldwide with the highest level of drill performance. Precision engineering and expert application support make Allied the first and best choice for solving complex metal-cutting challenges.

3E^TECH combines precision adjustment measurement in the tool with an external, dockable and detachable digital display that shows the adjustment setting. This user-friendly, micro-precision readout capability facilitates reliable machining processes for high-precision components. A sensor unit fitted to the display makes direct contact with the tool to record the adjustment travel. Wired, Bluetooth or magnetic connections are not required.

As of June, the 538052 (537052) precision boring cartridge is equipped with 3E^TECH. Made of hardened steel, it is extremely robust and resistant to all external mechanical influences. It can be used on serrated tool bodies and Alu-Line slide tools in the diameter range from 3.937” – 128.15” (100 mm – 3255 mm). Additionally, this precision boring tool can be adjusted without the aid of the readout. Its diameter can be set via a vernier scale in 0.0001” (0.002 mm) increments. This new tool offers an excellent price/performance ratio with extreme accuracy and strength in any industry. A simple analog version without 3E^TECH compatibility 538051 (537051) is also available.

External display compatible with all Wohlhaupter tools

The 3E^TECH display unit docks onto the tool and is activated via a pushbutton. It then shows the relative adjustment value of the tool in 0.0001” (0.002 mm) increments of the diameter to enable high-precision boring. Because the readout attaches externally and is not built-in, it can be used with all Wohlhaupter tools that are equipped with 3E^TECH sensor units. The external display is particularly suitable for tools having a small body diameter and for special tools with one or more adjustment units.

Detaches safely if spindle starts unintentionally

Built-in readouts can get damaged during the machining process, and magnetized solutions can be susceptible to data loss if the contact is broken. However, 3E^TECH provides the capability to store measured values in the tool itself to prevent data loss. The patent-pending interface between the digital readout and the tool ensures safe detachment in the event of an unintentional spindle start and protects the operator if the display is inadvertently left on the tool.

“The new Wohlhaupter 3E^TECH 538 (537) cassettes provide the ultimate combination of convenience and versatility—the perfect solution for your large diameter precision boring applications,” shared Natalie Wise, product manager.

About Allied Machine & Engineering:

Allied Machine & Engineering is a leading manufacturer of holemaking and finishing tooling systems. Allied devotes its advanced engineering and manufacturing capabilities to creating the widest selection of value-added tooling available to metal-cutting industries around the world. Our tooling solutions deliver the lowest cost per hole in a wide range of drilling, reaming, threading, boring, and burnishing applications.

Located in Dover, Ohio, Allied’s precision holemaking technologies provide end users worldwide with the highest level of drill performance. Precision engineering and expert application support make Allied the first and best choice for solving complex metal-cutting challenges.

As the most recent addition to the T-A Pro high-penetration drilling system, this insert demonstrates that the best just keeps getting better. Not only are the faster penetration rates maintained, but in using the redesigned body of the T-A Pro, maximum coolant flow and excellent rigidity are also present when utilizing the high-speed steel geometry. This offers machine shops and manufacturers a spade drill that operates at incredible speeds and a cost per hole that averages 25% less than other existing drills.

With a tool life that rivals carbide, the high-speed steel geometry insert works well in almost every material class. Allied Machine’s team of engineers developed this insert as the simplest solution for selecting a drill insert when hole quality, tool life and process security are the primary needs of the application. Ultimately, even in the toughest cutting conditions, this insert provides excellent hole quality for use in job shops and large part manufacturers such as heavy equipment and aerospace.

T-A Pro’s high-speed steel geometry insert series Z-3 is now available in diameters ranging from 0.437”-1.882” (11.10mm – 47.80mm). For more information on the “X” geometry, Allied Machine’s newest insert tailored for high-speed steel, visit http://www.alliedmachine.com/tap-hss

About Allied Machine & Engineering:

Allied Machine & Engineering is a leading manufacturer of holemaking and finishing tooling systems. Allied devotes its advanced engineering and manufacturing capabilities to creating the widest selection of value-added tooling available to metal-cutting industries around the world. Our tooling solutions deliver the lowest cost per hole in a wide range of drilling, reaming, threading, boring, and burnishing applications.

Located in Dover, Ohio, Allied’s precision holemaking technologies provide end users worldwide with the highest level of drill performance. Precision engineering and expert application support make Allied the first and best choice for solving complex metal-cutting challenges.

Is the Next Contract Long-Term or a Short Run?

If the answer is running a long-term, repeatable process, invest in a replaceable insert drill. Commonly referred to as a spade drill or replaceable tip drill, these drills are engineered so that machine operators have the ability to change out the worn cutting edge quickly. This reduces the overall cost per hole in high production runs. The initial investment of the drill body (insert holder) is compensated quickly by the reduction of cycle time and cost of replacing inserts versus the cost of new solid tooling. Simply put, speed of changeout coupled with a lower long-term cost of ownership makes replaceable insert drills the better choice for high production jobs.

If the next project is a short run or custom prototype, then a solid drill is the better choice due to the initial low cost. Since it is not likely that the tool will wear out while machining smaller jobs, the ease of cutting edge replacement is irrelevant. For a short run, the replaceable tool is likely to have a higher initial cost than a solid drill, so it may not pay dividends to invest. Lead time can be better for a solid tool as well, depending on the source for these products. With solid carbide drills, efficiency and cost-savings can be maintained when machining a wide range of holemaking applications.

How Much Stability is Required for This Job?

Consider the dimensional stability of a reground solid tool versus replacing the worn cutting edge with a fresh blade. Unfortunately, with a reground tool, the diameters and lengths of the tool no longer match the original version; it is smaller in diameter, and the overall length is shorter. The reground tool is used more often as a roughing tool, and a new solid tool is needed to meet the required finished dimensions. By using the reground tool, another step is added to the manufacturing process to make use of a tool that no longer satisfies the finished dimensions, thus increasing the cost per hole in each part.

How Important is Performance for This Particular Job?

Machine operators know that solid drills can be run at higher feeds than replaceable tools of the same diameter. Solid cutting tools are stronger and more rigid as they have no connection to fail over time. Nevertheless, machinists opt to use uncoated solid drills in order to reduce time invested in regrinds and lead times on reorders. Unfortunately, using uncoated tools reduces the superior speed and feed capabilities of a solid cutting tool. At this point, the performance gap between solid drills and replaceable insert drills is almost negligible.

What is the Overall Cost Per Hole?

The job size, initial cost of the tool, downtime for changeouts, regrinds and touch-offs, and number of steps in the application process are all variables in the cost of ownership equation.

Solid drills are a smart choice for short runs due to their lower initial cost. Generally, small jobs do not wear a tool out before they are complete, meaning there is no downtime from changeouts, regrinds and touch-offs.

A drill designed with replaceable cutting edges can offer a lower cost of ownership over the life of the tool for long-term contracts and high production runs. The savings start when the cutting edge is worn or damaged because there is no need to order the whole tool—only the insert (a.k.a. blade).

Another cost savings variable is the amount of machine time saved or spent when changing out cutting tools. The replaceable insert drill’s diameter and length are not affected by changing out the cutting edge, but since the solid drill needs reground when it is worn, solid tools should be touched off when replaced. This is a minute that parts are not being produced.

The last variable in the cost of ownership equation is the number of steps in the holemaking process. Replaceable insert drills can usually complete the process to spec in a single operation. Many applications that incorporate solid drills add a finishing operation after using the reground tool to meet the job’s requirements, creating an unnecessary step that adds machining cost to the part produced.

Overall, most machine shops need a good selection of drill types. Many industrial tooling suppliers offer expert guidance in selection of the best drill for a particular job, and tooling manufacturers have free resources for determining the cost per hole to help aid in the decision process.

About Allied Machine & Engineering:

Allied Machine & Engineering is a leading manufacturer of holemaking and finishing cutting tool systems. Allied devotes its advanced engineering and manufacturing capabilities to creating the widest selection of value-added tooling available to metal-cutting industries around the world. Their tooling solutions deliver the lowest cost per hole in a wide range of drilling, reaming, burnishing, threading, and boring applications. Located in Dover, Ohio, Allied’s precision holemaking technologies provide end users world-wide with the highest level of performance. Precision engineering and expert application support make Allied the first and best choice for solving complex metal-cutting challenges.

Stainless steel is offered in varying grades based on specific properties. These grades are also split into groupings based upon metallurgical qualities. Outlined below are the different families of stainless steel.

• Austenitic – A rather common material, austenitic steel is identified as the Type 300 series; grades 304 and 316 are the most accessible. While austenitic stainless steel cannot be effectively heat treated, it can be hardened through cold working—the process of changing the shape without the use of heat. Corrosion resistance, low magnetism and good formability are also characteristics associated with this family of stainless.
• Ferritic – As part of the Type 400 series, ferritic stainless steels are characterized by their corrosion resistance, strong ductility and magnetism and are typically iron-chromium alloys. This family can be altered through cold working rather than thermal hardening methods.
• Martensitic – Similar to ferritic stainless, martensitic are also iron-chromium alloys within the Type 400 series; however, this grade is able to be hardened by heat treatment unlike the ferritic grade. Other characteristics include magnetism, good ductility and corrosion resistance.
• Precipitation-hardened (PH) – Through the precipitation hardening process, precipitation-hardened stainless steel attains more strength in addition to greater corrosion resistance. Additionally, it is similar to martensitic stainless in terms of chemical makeup.
• Duplex – With a composition made up of nickel, molybdenum and higher chromium levels, duplex stainless steels combine features of ferritic and austenitic stainless, yet this family demonstrates greater strength and high localized corrosion resistance.

Whether machining valve choke bodies for the offshore oil industry (410 stainless), pump covers for the food processing industry (316 stainless steel), bushings for the aerospace industry (17-4 stainless steel) or pumps for the water and wastewater industry (304 stainless steel), knowing and understanding the varying grades and properties of stainless steel will enable machinists to effectively utilize stainless steel and overcome its challenges when they arise.

One of the greatest challenges of machining stainless steel is chip control. Alloying elements such as nickel cause stainless steel to be partially heat resistant, which results in difficulty forming a chip and, thus, poor chip evacuation. In typical steel cutting applications, heat transfers into the formed metal chip. When machining stainless, the heat resistant nickel alloys prevent this heat transfer. This leads to higher cutting temperatures and increased rates of tool deterioration when compared to common steel machining. Simply stated, the nature of the material and its high amount of elasticity make it difficult to achieve chip formation and induce quite a bit of wear on the cutting tool.

Combatting these challenges can be done a few ways—one of those being understanding machine conditions. While machine type does play a small factor, machine condition is more detrimental. Machinists must ask themselves, is the spindle rigid? Is the alignment reasonable or near zero runout on a lathe? Knowing these factors can greatly benefit or cause significant issues when trying to machine stainless steel. Additionally, running through the tool coolant provides significant tool life advantages over flood coolant. Ultimately, due to its alloying elements, more torque and horsepower are required to drill stainless than typical steel or aluminum materials.

These challenges in stainless applications can also be resolved by working with a more aggressive geometry to attempt to get the chip to form. In austenitic stainless like 316, it is best to use a geometry with a higher rake angle to produce a more manageable chip; however, when working with a harder material such as PH stainless, this method is not effective. In this instance, increasing the rake angle causes the cutting edge to weaken—in turn reducing tool life. With harder materials, this makes the negatives often outweigh the positives.

Nevertheless, the benefits of stainless are so numerous that it is beneficial to overcome these challenges when possible. Corrosion resistance is one of the key benefits of stainless steel. Because a number of grades of stainless are highly corrosion resistant, it is the material of choice in applications where weather or corrosive materials will be in direct contact. For example in the energy industry, electrical wiring that is run through the ocean for offshore wind farms is made out of stainless steel or a high temp alloy material because of its corrosion resistance, which does not allow salt water to negatively impact it as it does other materials. Similarly, offshore drilling utilizes stainless steel because of the corrosive and abrasive materials that are being pumped through these lines.

The food industry is another industry where stainless steel is often used. Stainless steel’s chromium composition, which must be a minimum of 10%, is highly reactive to oxygen environments. This forms a strong, unreactive barrier on the surface of stainless steel, making it the material of choice for the food industry. Finally, the naturally high strength of stainless steel as well as its resistance to corrosion and weather make it a vital material for the aerospace industry in terms of precision parts, fittings, and other components.

All in all, stainless steel is not a material that can be brought into a machine shop to machine straightaway; every aspect must be reviewed prior to machining stainless steel. Not only do machinists need to firmly understand the different grades of stainless and their properties, but they also need to examine machine capabilities. Yes, tool wear and excellent chip formation are challenges that one will face when drilling stainless. Fortunately, these can be managed through proper coolant usage and correct choice of insert geometries, coatings and substrates. Making the best selections can be simplified by consulting cutting tool experts like those at Allied Machine and Engineering as well as coolant specialists. For technical support in holemaking and finishing in stainless steel, call (330) 423-8243 or visit www.alliedmachine.com. Rememeber, one cannot get away with just anything when machining stainless steel.

About Allied Machine & Engineering:

Allied Machine & Engineering is a leading manufacturer of holemaking and finishing tooling systems. Allied devotes its advanced engineering and manufacturing capabilities to creating the widest selection of value-added tooling available to metal-cutting industries around the world. Our tooling solutions deliver the lowest cost per hole in a wide range of drilling, reaming, threading, boring, and burnishing applications.

Located in Dover, Ohio, Allied’s precision holemaking technologies provide end users worldwide with the highest level of drill performance. Precision engineering and expert application support make Allied the first and best choice for solving complex metal-cutting challenges.

VolCut combines the benefits of the modularity of the Wohlhaupter MVS connection with Allied Machine and Engineering’s large diameter holemaking solution. This time-saving combination offers increased material removal and excellent chip control at greater depths for large diameter applications – even on underpowered machines. The VolCut insert holder is stocked for quick delivery with bore diameters ranging from 2.559” – 128.149” (65mm – 3255mm). Its unique design incorporates serrations designated to connect seamlessly with Wohlhaupter’s Twin Cutter and AluLine boring systems.

Manufacturers pre-machining large diameter holes in components for the oil and gas and heavy equipment industries can reduce cycle times with VolCut’s high cutting speed and material removal up to 2.755” (70.00mm). The company reports case studies show cycle time reductions up to 80% when compared to similar circular milling applications. The indexable inserts utilized by VolCut shorten process times even further by allowing the tool to remain engaged in the spindle while worn cutting edges are changed out. Allied Machine and Engineering stocks the indexable inserts as standard items ensuring quick replenishment.

Natalie Wise, USA product manager of the Wohlhaupter boring line, states, “The VolCut insert holders provide a rough boring solution unmatched by other rough boring competitors. The ability to utilize the VolCut insert holders with your existing standard Wohlhaupter modular tooling provides the additional range needed to vastly improve your rough machining operations.”

The VolCut insert holders and indexable inserts are available to order from Allied Machine and Engineering’s distributor partners.

About Allied Machine & Engineering:

Allied Machine & Engineering is a leading manufacturer of holemaking and finishing tooling systems. Allied devotes its advanced engineering and manufacturing capabilities to creating the widest selection of value-added tooling available to metal-cutting industries around the world. Our tooling solutions deliver the lowest cost-per-hole in a wide range of drilling, reaming, threading, boring, and burnishing applications.

Located in Dover, Ohio, Allied’s precision holemaking technologies provide end users worldwide with the highest level of drill performance. Precision engineering and expert application support make Allied the first and best choice for solving complex metal-cutting challenges.

About Wohlhaupter Gmbh:

Established in 1929, Wohlhaupter continues to manufacture the widest range of precision boring tools and systems available in the marketplace and has been the consistent leader in technological innovations for improving precision boring operations.

In 2016 Allied Machine and Engineering purchased the majority shares of Wohlhaupter. Together, Allied Machine and Engineering and Wohlhaupter provide precision engineering and expert application support to provide cost-effective holemaking and finishing solutions for today’s manufacturers worldwide.