02/04/96 SHopcoST version 2.0 Machine Capacity: The purpose of this document is to provide the user with data on some of the factors, which determine Machine Capacity and Machining Time for SHopcoST 2.0. The energy required to cut a material is a product of cutting speed and cutting force. By determining how much cutting energy is required to remove material, it can be determined at what horsepower level the machine is functioning. The method for determining the horsepower level is the power constant for various materials and conditions. The power constant alone does not determine the cutting energy, but provides a proven method for computing the power at the motor. The factors which do not influence the Power Constant are: 1. The Cutting Speed. 2. The Depth of Cut. 3. The Cutting Tool Material. The factors which influence the Power Constant are: 1. The Material Hardness. 2. The Feed Rate. 3. The Rake Angle of the cutting tool. 4. Tool Wear, or the condition of the cutting edge. 5. Chip Breaker. 6. Cutting Fluid. (low cutting speeds) 1. THE MATERIAL HARDNESS: At present Shopcost version 2.0 includes seven different types of materials and various Brinell hardness levels. Plain Carbon Steel- Low, Medium or High carbon content from 80 to 360 Brinell Hardness. Free Machining Steel- American Iron and Steel Institute values are given from 1108 to 1151, and their hardness. Alloy Steels- American Iron and Steel Institute values are given from 1330 to 8740, and their hardness. Gray Cast Iron- 100 to 240 Brinell Hardness. Alloy Cast Iron- 150 to 250 Brinell Hardness. Tool Steel- 175 to 400 Brinell Hardness. Stainless Steel 150 to 250 Brinell Hardness. 2. THE FEED RATE: Feed rates from .001 to .060 are given, and reflect the feed in inches per revolution for turning or chipload per tooth for milling. Example: A turning operation of .018 inches per revolution, requires the cutting tool to move at .018 thousandths of one inch per 1 revolution of the part. Example: A milling operation of .005 chipload per tooth, will produce a chip of that given thickness, depending on the feedrate in inches per minute. Chip thickness effects the life of the milling cutter. 3. THE RAKE ANGLE OF THE CUTTING TOOL: The rake angle can be disregarded, but with this software, the rake angle of the tool is based on a positive 14 degrees. Using a rake angle that is more positive reduces the power required by one percent per degree. Using a rake angle that is more negative increases the power required by one percent per degree. 4. THE TOOL WEAR FACTOR: The tool wear factor comes into to play when you see one of the two screens in the turning or milling operations: What type of turning operation is it. ? Finish Turning(lightcuts) Normal rough and semi-finish turning Extra-heavy duty rough turning What type of milling operation is it. ? Slab milling End milling Light and medium face milling Extra-heavy duty face milling In both cases, the cutting speed will decrease and the horsepower requirement will increase, as you go from a Normal or Medium operation to an Extra-heavy duty operation. Really all it's doing is allowing a condition for sharp tools or expected tool wear. Try a few experiments to see what I mean, while programming in the same values except here. Behind the scenes: If your planning a turning operation, and your inserts have been indexed or your tooling is sharp, you could Enter 1 for Finish turning(Lightcuts). By entering 1, you have programmed in the best possible condition of your tooling, and your cutting speed will increase slightly, but won't demand more horsepower. Try not to use this technique much of the time, because if you're running a lot of parts, it's best to use an operation which describes the type of tool wear to be expected from that operation. 5. CHIP BREAKERS: Chip breakers may reduce the power needed to cut the same material, but has not shown to be true or false. 6. CUTTING FLUID: Some cutting fluids may reduce the power needed at lower cutting speeds, but could be counter-productive for high-speed applications. High-speed, high-temperature cutting, tends to promote better shear flow and thus reduces the cutting force and power needed. Actual Capacity: Based on the attributes that you give, such as feed, depth of cut and cutting speed for starting conditions, it will compute how much cutting energy is needed at the tool, and how much horsepower the machine needs, with the following efficiency rating: 90% efficiency rating for a direct belt drive. 75% efficiency rating for a back gear drive. 75% efficiency rating for a geared head drive. (middle) 70% efficiency rating for a oil-hydraulic drive (low) Behind the scenes: If you have a gear driven machine that you feel is higher than 75 percent, and closer to 90% efficient, then go with the belt drive. These values are based on averages only, and may not reflect the rating of your machine, but usually their close. Actual capacity then is the required HP needed to machine the part, with the values given. Available Capacity: Based on how much horsepower is actually needed to produce the part, we'll get a relationship between actual and potential capacities. The difference between what's needed, and what your machine has to offer, are the available capacities. Available capacity is the max. machining performance, that your motor will allow, for the values given. Metal Removal Rates: From the actual and available capacities, we can determine the rate of metal removal (cu.in.\min). The MRR is shown at the bottom of each bar graph, just above the HP ratings. Would you say that MRR has minimum and maximum values?, not always, because you could over-shoot the capacity of your machine, and end up with an actual MRR that's greater than what your machine can deliver. The MRR values are a range between two capacities, which are the actual and available respectively. Machining Time: In the final modules of Shopcost, we can compute the Machining Time for turning or milling, based on the two capacities we've produced. The purpose of the Machining Time function here is to utilize the range of our capacities, therefore, Shopcost 2.0 will only consider the roughing cycle in it's determination for machining time. What the Machining Time feature does consider: 1. The least required or actual horsepower needed to machine the part. 2. The best performance or available capacity that your machines motor can give. 3. The amount of material to be left for finishing. 4. The time it takes to return the tool, feed in and begin another pass, from multiple passes, which are based on the machinists own estimation of a single pass. What the Machining Time feature does not consider: 1. The finish cycle, which would include a tool change, on a manual machine, or indexing the tool changer. 2. The time required to index the insert, or sharpen the tool as a result of excessive tool wear or chipping. 3. Drills, Taps, Boring bars or other tools which would require changeover time from a turning or milling operation. 4. The time required to load and unload the parts. If you want to make any suggestions as to improving Shopcost for future use, please feel free to do so. Included with the program, are my e-mail and mailing street address. Their are several help files built in, but their only in places that would benefit from them. Their Hasn't been a discussion about the Round and Bar stock components of the program, because I hope their self-documenting. Shopcost 2.0 was written with a combination of "C" "C++" and Object oriented programming. It stands now at 48 modules and compiled 63k lines. The project was mostly developed on weekends using Borland Turbo C++ 3.0., with many sources of information. Shopcost 2.0 author: John Scheldroup home: 406 E. 9th St. Superior, WI 54880 email: jschel@aol.com have a nice day