| |MARCH 20219A 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 runsWhat 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 choicefor 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 hole-making 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.
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