Economy of high performance drilling in the hottes

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In reality, the economy of high-performance drilling

high performance cemented carbide bits have two major characteristics:

compared with high-speed steel or traditional cemented carbide drills, the drilling quality is high, the speed is fast, and the service life is long

the cost of high-speed steel or traditional cemented carbide bits is much higher

so, does it have so many advantages that it is worth investing in? Not always. And it is not always possible to draw conclusions by analyzing short-term costs. Evaluating the economy of high-performance bits involves a variety of factors

this paper mainly expounds these factors. A simple and realistic drilling example is used as the model. Although the numbers used to analyze this workpiece are based on approximation and assumptions, so they cannot be directly applied to a specific workshop or application, the logic used in the analysis can be applied to a large number of drilling operations. The analysis shows that the cost-effectiveness of a specific bit can be determined by some factors that have nothing to do with the initial cost of the bit


analysis is based on the simple drilling operation in the figure below. Here are some details involved:

the workpiece material is a kind of steel with appropriate processing properties, which is processed on a single machining center

the production rate of this part is 15 pieces per hour, the real net average value

the workpiece extends the service life of the tool; To improve the critical cutting depth for the transition between brittle and ductile domains, four holes need to be drilled, with a hole diameter of 0.531 inch and a hole depth of 1.250 inch

their top has innovative shape and geometric characteristics, which is part of the reason for their good processing performance. These complex centers require very high grinding accuracy

the following prices are some typical known resources that can process high-quality and top-notch products. Coating is also a cost that must be included

once the paint surface of steel is damaged or the early anti-corrosion is not well done, it is easy to rust and corrode. The workpiece is processed for 16 hours in two shifts every day, 5 days a week

the workshop adopts the unit time pricing system, which is $60 per hour, including machine tool costs, labor and miscellaneous expenses

basic bit performance

let's first look at the basic measurement factor of bit performance: cutting speed. Two cutters are used for comparison - a typical high-quality high-speed steel drill and a high-performance cemented carbide drill. The displayed speed and feed speed are based on the manufacturer's recommendations, combined with basic common sense and experience. Of course, cemented carbide drilling speed is higher. If the cutting time is converted into cost, the following results will be obtained:

basic bit cost

now let's add some other important information, such as the cost of the bit and the expected cutting life

the drilling speed of cemented carbide is 2.5 times faster than that of high-speed steel drill, and its service life is 5 times longer, but its price is nearly 18 times higher. Therefore, the basic cost of machining a hole is high. But in our calculation, there is another part that is not considered is the cost and performance after the first life cycle

bit maintenance

the following table shows the basic cost of bit regrinding. Assume that the standard high-speed fried dough twist drill is reground with a tool grinder that is not very expensive within the company. It is assumed that the hourly price of the workshop is $60. The average sharpening time is assumed to be 5 minutes. It is impossible to grind cemented carbide bits with ordinary drill grinder or grinding fixture. This is because their top has innovative geometric characteristics, which is part of the reason for their good processing performance. These complex centers require very high grinding accuracy

the following prices are some known resources that can process high-quality top-notch products. Coating is also a cost that must be included

real production cost

regrinding cost value assumes that each drill bit is ground 10 times before it can no longer be used. If we combine the cost of buying drill bits with all regrinding costs, and then consider the long-term overall performance of the two tools, we can get a more accurate conclusion about the real cost incurred

the following table considers six months (25 weeks) of production. Based on the assumptions given, 120000 holes can be machined

inventory cost

now the difference becomes obvious. Using high-performance cemented carbide bits and competent regrinding equipment can reduce the drilling cost of parts by almost 40%. However, when the sample is artificially aged, the analysis is not over

we assume that cemented carbide bits are outsourced regrinding, so what bits do we use while waiting for the regrinding bits to return? The natural answer is to use a spare drill. The number of spare drills will depend on the turnaround time required for regrinding

based on the production rate, the number of holes and the service life of the drill bits we used earlier, roughly two drill bits will be worn out every working day. It means that two spare drill bits are needed every day while waiting for regrinding. The number of bits to meet this need may be very high. As shown in the table below, it is very important to control the delivery time of regrinding

cost control

one way to fully control the regrinding operation and reduce its cost is to complete the operation in the company. Since conventional bit regrinding equipment cannot complete this operation, new equipment is required. An example of such a device that may be required is shown in the photo. CNC machine tools may cost a lot, but in some cases, outsourced regrinding may cost more for static bending strength

we have been using the assumption of $60 pricing, including machine tool costs, labor and miscellaneous costs. It is also assumed that 10 drill bits are ground per hour. The table shows the overall savings in the 10 regrinding life of a drill bit

final analysis

the proposed internal plan of the company can save $12 for each regrinding, or $120 in the life of each drill bit. If these savings are included in the long-term operating cost comparison, the total drilling cost of the workpiece can be reduced by $15099. Compared with outsourcing regrinding, this can save more than 2600 dollars, and compared with the use of high-speed steel bits, it can save 14000 dollars

please remember that these savings only come from a drill bit, a workpiece and a 6-month cycle. For a typical production plant with a small number of drilling machines or machining centers, the potential for savings is greater

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