If you want to learn more, please visit our website.
TABLE OF CONTENT
Choosing a drills composition will vary depending on its use. Generally, drill bit materials are available in three categories.
HSS drills are a good choice for drilling soft steels and plastic. They are economical and adaptable for many drilling applications.
With the addition of 5-8% of cobalt, HCSCO drills provide improved hardness and wear properties and are suitable for drilling steel, cast steel, titanium and other hard materials.
Carbide drills maintain sharpness more than any other drill material and are best for the hardest materials, including ceramics, glass, stainless steel and cast iron. While outperforming all other drill materials, carbide drills are brittle and more expensive.
Drills can be custom made to virtually any size, depending upon the application. However, industry standards have set defined drill sizes that are most commonly produced by drill manufacturers.
Drill lengths are also variable, however, there are defined types:
Drill geometry is the complex relationship between the various angles and aspects of the drill. The length and bore of the drill along with the configuration of its cutting edges, flute profile and point angle impact performance, accuracy and tool life.
Optimizing these relationships to the application, production goals and workpiece is essential to efficient, cost-effective drilling.
Components of drill geometry to be considered are:
A drills rake or helix angle is the angle between the drills leading edge and its axis. Rake angles are generally available between 18 and 45 degrees with 30 degrees being the typical value. Higher rake angles form tightly rolled chips. Lower rake angles tend to form chips that are more loosely rolled. Rake angles also affect cutting temperature and tool life.
Large rake angles are generally employed when drilling softer materials, while smaller angles are used when drilling hard materials that produce smaller, shorter chips.
DIN addresses helix angles with three groups:
A drills cutting edges are connected by the chisel edge and are responsible for the actual drilling process. Long cutting edges provide better performance in the drilling process.
Find the Right Drill with our guide/whitepaper
The goal of metal cutting applications, including holemaking, is to keep tooling and operational costs low and
output high.
While many manufacturers carefully consider the tools they use for milling and turning, they may not treat the
selection of holemaking tools as an equally critical decision, but they are.
Tips and tricks are always welcome.
Learn more here
There are a variety of coatings available for drills, each with specific advantages and more appropriate than others for specific applications. As in most tool selection questions, the answer to which is best is primarily driven by the operation and workpiece. Drill coatings also extend tool life, thereby reducing the overall cost per hole.
Coatings are generally applied to drill cutting edges via a process called Physical Vapor Deposition (PVD). PVD uses a physical process such as heating or sputtering to produce a vapor of material that is then deposited on the object being coated.
The most common drill coatings are:
The primary disadvantage of coated drills, however, is that they sometimes cannot be resharpened.
Coolant and lubrication during the drilling process significantly improves tool life, chip evacuation and hole quality, especially in tough workpieces such as alloyed or stainless steels. Heat reduction is even more important in drilling operations because most of the energy is transformed into heat. In drills with multiple land margins there is more contact between the hole surface and the tool, making heat control even more important.
There are several different types of coolant available, and selection is dependent upon the application. Among them are:
Internal coolant is always recommended for drilling and is the best option for tough work materials such as super alloys and stainless steel. For effective internal cooling, through-cooling tools have cooling channels that direct coolant directly to the cutting zone.
If external coolant is used, it is important to ensure the coolant flow is directed as parallel as possible to the drill as it reaches the cutting area. For acceptable chip evacuation, the maximum recommended drilling depth using external coolant should be no more than 3X diameter and reduce cutting speed by 20% as compared to operations using internal coolant.
Though there can be any number of issues that arise, by far the most concerning is drill breakage. Broken tools obviously have to be replaced at the expense of time and money, but they also increase the risk of scrapped parts and waste.
Goto SINOCOREDRILL to know more.
Some causes of drill breakage are:
Efficient drilling requires minimizing cost per hole. Drills that wear too fast require downtime for changing tools, and that increases cost per hole. To avoid changing tools too often:
Chipped cutting edges will not drill a quality hole. Chips on the cutting edge can be caused by:
Chips that fail to break become long and stringy requiring work interruptions to unwind them from the tool. To keep chips in check:
Follow these general guidelines for cost-effective, sustainable drilling.
Shorter drill bits decrease the drills ability to wander or stray from its starting point during the drilling process. As a result, shorter drill bits provide more accuracy. Because they are more rigid, they are less likely to break and are easier to use in confined areas.
A self-centering drill geometry allows for precise and accurate hole placement, eliminating the need for additional alignment tools or excessive adjustment. The drill automatically centers itself within the starting point, ensuring the hole is perfectly positioned to part requirements. Self-centering drills save time, simplify setups and reduce cost per hole.
Use drills engineered to prioritize secure drilling and maintain position throughout the drilling process to minimize unintended movement or deviations. Stability is critical for achieving accurate, consistent results, particularly when working on delicate, complex parts where precision is paramount.
Efficient chip evacuation and preventing chip buildup is essential for smooth drilling and maximizing productivity. Proper chip evacuation reduces downtime, enhances drilling performance and promotes overall productivity in the machining process.
For deep hole drilling and long drills exceeding 16XD, a pilot drill will be necessary. Drilling a pilot hole first will remove some of the material from the workpiece and reduce the force necessary to produce the final hole. Pilot holes decrease hole runout and assure maximum accuracy.
If drilling into an angled surface, machine a flat using a solid end mill via the interpolation method. If milling is not possible, reduce the drilling feed by 50% until the drill has reached full cut. Use a drill with multiple land margins and reduce feed rate by 30 to 50% during exit.
To drill cross holes, reduce feed by 50% 3mm before the crossing and maintain that low feed rate up to 3mm after passing the crossing hole. If possible, use a multiple land margins drill to improve guiding.
Stacked materials can be drilled effectively as long as the workpieces are clamped securely so that there are no air gaps between them. Air gaps have a detrimental effect on chip evacuation and cause drill damage.
Choosing the best tool for a given application involves a broad range of considerations. Apart from universal drill geometries that are versatile and adaptable to changing applications and production needs, selecting a drill with the right features, dimensions, coatings and cutting characteristics will directly impact your performance.
For sustainable drilling at the most efficient cost per hole, contact a Seco expert to find the right tool for your job or try Suggest.
Holemaking is a pretty common procedure in any machine shop, but selecting the best type of cutting tool for each job isnt always clear cut. You want a drill that caters to the workpiece material, produces the specs required, and ultimately provides the most profit for the job at hand.
So, which drill provides the most value? When it comes down to the variety of jobs manufactured in your machine shop, there is no one-drill-fits-all. According to experts from Allied Machine & Engineering, you can simplify the process by considering five criteria when choosing between two big players in the world of metal-cutting: solid drills and replaceable insert drills.
Is your next contract long-term or a short run?
Ask yourself if this particular job is a high production run of the same part or is it a custom prototype or small batch of components?
If you are running a long-term, repeatable process, invest in a replaceable insert drill, like the T-A Pro drill manufactured by Allied Machine and Engineering. 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 these types of high production runs. The initial investment of the drill body (insert holder) is recouped 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 your high production jobs.
Both solid and spade style drills can each offer cost-savings, but there is no one-drill-fits-all when it comes to the variety of jobs processed on most machine shop floors.
If your next project is a short run or custom prototype, then a solid drill is the better choice predominantly due to the initial low cost. Since youre not likely to wear the tool 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 its solid cousin so it may not pay dividends to invest. Lead time can be better for the solid tool as well, depending on your source for these products. Between solid carbide drills like the ASC 320® and Superion® lines of solid carbide tooling, youll be able to machine a wide range of holemaking applications with efficiency and cost-savings.
Superion offers custom solid carbide tools which can be engineered to combine multiple steps in one tool for reduced cycle times.
How much stability is required for this job?
Consider the dimensional stability of a reground solid tool vs 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. When you regrind a tool, it is smaller in diameter and the overall length is shorter. The reground tool is used more often as a roughing tool at this point, and a new solid tool is needed to meet the required finished dimensions in the workpiece. By using the reground tool, you add another step to the manufacturing process to make use of a tool that no longer satisfies the finished dimensions. This ultimately increases your cost per hole in each part being made.
Are there inventory requirements to consider?
Tool float is the total number of tools in the machine shop environment needed to avoid downtime. In order to keep the job running, you need to maintain a certain amount of tool float inventory. This includes tools at the machine, back ups in the tool crib, and even tooling waiting to be reground. Lets look at two scenarios.
Scenario one Currently you need to keep three solid drills at the machine to maintain uptime for this job. You have 12 on hand in the tool crib in case of catastrophic failure as well as six out for regrind at any given time. In this situation you need 21 solid carbide drills in the system to keep the machine running.
Scenario two For the same job in scenario one, you only need two replaceable drill bodies and four inserts at the machine and four bodies and 12 inserts in the tool crib. Since you wont have to accommodate for tools out for regrind, you can keep the same job running smoothly while significantly reducing the amount of inventory needed.
With long-term jobs, replaceable insert drills offer the ease of quick insert changeouts while the same tool body remains engaged in the machine spindle.
How important is performance for this particular job?
Any machine operator knows that solid drills can be run at higher feeds than indexable tools of the same diameter. Solid cutting tools are stronger and more rigid as they have no connection to fail over time. At times though, 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, so take this into consideration when making your decision.
Finally, what is the overall cost per hole?
Lets talk about tool life and cost of ownership again. 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 dont wear a tool out before they are complete. This means there isnt any 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, you only pay for 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 drills diameter and length are not affected by changing out the cutting edge, but since the solid drill needs reground when its worn, solid tools should be touched off when replaced. While this only takes a minute, its a minute that you arent producing parts.
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. As was mentioned earlier, many applications that incorporate solid drills add a finishing operation after using the reground tool in order to meet the jobs requirements. In reality, it may be an unnecessary step that adds machining cost to the part produced.
Overall, most machine shops need a good selection of drill types. Most industrial tooling suppliers offer guidance in selection of the best drill for a particular job and tooling manufacturers have free resources like worksheets for determining the cost per hole to help aid in the decision process as well.
The company is the world’s best Surface Drillngtooling supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.