Quality Machining at CNC Precision Manufacturing

CNC Precision Manufacturing, Machining Workshop in the Greater Portland Area

CNCPMI Turns to EdgeCAM High-End Capabilities

Machining Solution to Global Competition
Brings Complex Parts, Complicated Processes

Contract machining shops in North America can prosper despite tough global competition with multi-tasking CNC machine tools—especially combination turning and milling or “mill/turn” centers. They can manufacture parts in one setup—sometimes called “one hit” machining—rather than multiple setups on several different machines.

Mill/turn machines open doors into fast-paced new markets for very short-run jobs and prototypes. However, these machines are costly to buy and complicated to run efficiently. Mastering their programming and complexities demands great skills and discipline. At-the-machine style “manual” programming is almost out of the question so a state-of-the art CAM system is an essential pre-requisite.

North American shops have adapted well to multi-tasking CNC turning and milling centers. They have:

• Learned to program and machine complex parts that have thousands of individual surfaces faster and more accurately than ever before.

• Learned how to handle ultra-short runs; orders averaging only 10 parts and often for just one.

• Learned to make profits on prototypes, even when there are many design changes.

All these can potentially transform the business of contract machining, to take these owner-operated businesses to new peaks of revenue and profitability. There are more prosaic productivity benefits, too. Downtime between milling and turning operations is eliminated. Part accuracy is increased because tighter tolerances can be held between milling and turning operations. Factory floor space is saved.

EdgeCAM's Feature Finder automatically discovers hole features on a prototype part for a motorcycle engine. Holes and pockets will be machined using X, Y, Z, C and B-axis positioning and coordinate conversion functions.

To support their new CNC turning / milling centers, shop owners are replacing CAD and CAM systems they relied on for years. Now they handle native customer part geometry, and design their own fixtures, with fully associative solid modelers. Slow, cumbersome wireframe-based CAM has been retired in favor of fully interoperable programming systems with workpiece visualization and toolpath simulation.

A classic example is CNC Precision Manufacturing Inc. (CNCPMI), a five-person firm in Sherwood, Oregon, near Portland. “Due to the length of time required to patch up old CNC code for a C-Y-B mill/turn part, usually programming was the most expensive and time-consuming part of a job. Now it is the fastest and least expensive,” said Mircea Moga, CNCPMI president and lead programmer.

Sample of Polar Coordinate machining by interpolating the C and X axis and using an axial end mill. This part was an aerospace prototype.

Moga tackled the CNC programming challenge head-on with EdgeCAM from Pathtrace Systems Inc., Southfield, Michigan. “EdgeCAM has helped us integrate multi-axis turning and milling in one easy-to-comprehend interface that exactly simulates the machine,” he said. “Understanding, programming efficiently and using a multi-tasking mill/turn CNC machine is not always an easy task because there are so many different functions, which machine tool builders install in different ways. It’s not like programming a CNC milling machine or a lathe.

The EdgeCAM interface helps programmers understand these machines’ many configurations, which in turn are the keys to their great versatility and the high productivity. Specifically:

• The C axis in a mill/turn machine is a rotary axis that is concentric with the main and sub spindle of a mill/turn center. The C axis can be used as an indexer or as a true C axis when it can be fed in degrees of a circle per minute. By interpolating the C and X axes, and sometimes Z, and using power revolving tools and polar and cylindrical coordinates, any shape can be cut on the face or the diameter of the part. This eliminates any need for any separate, secondary operations on another milling machine. By indexing the C axis, every side of a part can be machined.

• The Y axis on a mill/turn center is similar to the Y axis on a regular milling machine. Powered revolving tools are used to cut materials. On mill/turn centers the travel of the Y axis is usually short, yet combining C- and Y-axis positioning will enable a mill/turn center to machine all sides of a part. Perpendicular to the X axis, Y allows milling off the centerline of the main spindle.

• The B axis on a mill/turn center is a fairly new technology that allows powered tools. On some machines the whole turret can be angled from -5 to +95 degrees in the Z axis. These machines can then use virtual work coordinates (as in machining at an angle) to further increase the complexity of parts they manufacture..

Even more complex machines can work as a 5-axis mill with turning capabilities by allowing the B, C, X, Y and Z axes to be interpolated simultaneously or in groups. This is a far cry from 3-axis mills where X is simply side-to-side on a flat bed, Y is front to back and Z is up and down.

EdgeCAM using Cylindrical Coordinate Interpolation using C, X, and Z axis to mill a radial profile on a medical part.

All these axis options are available from different manufactures of CNC machines on the main and sub spindle. “The versatility makes these machines extremely complex and of course not too easy to program,” Moga said. “We at CNCPMI are handling the programming of all the axes seamlessly with the help of EdgeCAM.”

The EdgeCAM user interface allows side-by-side views of instruction browsers for each turret on mill/turn machines. This optimizes turret use, helps prevent turret and spindle conflicts, and allows synchronization points to be moved to minimize machine idle time. It is also indispensable for turret and spindle synchronization, collision avoidance, establishing turret priorities, and resolving potential conflicts.

Despite all these new complications, “programming a complex job now takes a fraction of the time it used to,” Moga added. “In addition, the EdgeCAM code is more accurate and cleaner than it ever was before. With our previous 3D wireframe CAM system, we were getting the job done but not very well. Programming here has gone from a bottleneck to an asset.”

The many technologies in EdgeCAM have made a huge change in CNCPMI’s operations. “Our programming is at least 20% more productive across the board and that jumps to 80% or better on complex jobs,” Moga said.

“The new CNC programs are also more efficient, he added, “and they let us take better advantage of the multi-function, multi-axis machine tools. We don’t have to worry any more that our machines are sitting idle and waiting for a new job to be programmed. Now programming is as fast as, or faster than, the machines.”

Even better: “Our biggest CAM productivity gains are on jobs that have the most complex geometry and the most complicated operations,” Moga said. “The more complex the job, the more competitive we are. EdgeCAM is helping us get more business from our [existing] customers, plus more profitable business from new customers, and more chips from the spindles.”

CHALLENGES: Complex Parts, Complicated Processes and Prototypes
The primary CNC machine tools at CNCPMI are
• A newer 5-axis Hitachi Seiki Super HiCell 250, milling-and-turning center with C, Y and B axes, a tool change magazine and an autoloader, installed early in 2004.
• A 4-axis Mori Seiki NL 2000 SMC milling-and-turning center with a C axis on the main and sub spindle, installed early in August 2005.
• A 5-axis Swiss Star with dual independent turrets with milling and a sub spindle.
• A Leadwell 40-inch, 3-axis machining center installed in early 2005.

There are also three older machines, a 3-axis CNC mill and two 2-axis turning centers that are dedicated to specific jobs. They don’t run all the time, but they are paid for.

All of them are programmed with EdgeCAM, he said, “and EdgeCAM gives us better control over the many new features in those machine tools. Sometimes we rewrite old existing programs using EdgeCAM and are able to reduce cycle times and make parts a lot faster.”

The challenge for shops like CNCPMI was not that business disappeared but that it changed drastically—and came from entirely new customers. Gone were the simple parts with long runs. Shops were suddenly confronted with complex parts, which presented all sorts of complications on the factory floor, just as order quantities shrank and delivery schedules tightened.

Sample of 3D Parallel Lace machining using X,Y and Z axis interpolation with a ball end mill on a medical part.

Meanwhile, prototype work—which many contract machining shops dislike— popped up everywhere. “Most shops took orders for prototypes,” Moga pointed out, “just to get the production business, which often they did not get anyway, or in hope of securing the customer’s future business. To me as a shop owner, that’s a poor investment.

“It was always very hard to make money doing prototypes because we didn’t have the systems to handle all the changes the customer wanted to make,” he added. “Now we actively seek out prototypes,” the beating heart of every new-product development initiative.

The obvious answer to the new demands for speed, complex parts and complicated processing was to invest in multi-function production machines but that merely shifted the problem from tooling to geometry. In machine tools, combined turning and milling reduces the number of setups to one or two per job instead of three, four or more. Said Moga, “usually with just one operation on a mill/turn machine we replace a second operation on a turning center and two ‘ops’ on a mill.” Fixturing is cut by a similar amount, and most time-consuming secondary operations are eliminated. “We can run faster and be more competitive on quality price and delivery.”

“Many of those new customers,” Moga said, “were companies that we did not dare approach before we got EdgeCAM. It would have taken us a week just to get a good CNC program. Now we can program those jobs from aerospace, electronics and other high-tech companies in two or three hours! This opens new doors for us. We are now getting very complex parts with thousands of surfaces.”

SOLUTIONS: Associativity + Interoperability + Visualization + Simulation
Some of CNCPMI’s biggest gains in speed come from CAM technologies including associativity, visualization and simulation. Here is how CNCPMI puts them to use. All the quotations are Moga’s.

Associativity with SolidWorks lets Moga import a customer’s solid model by bringing up EdgeCAM from inside SolidWorks. Once in EdgeCAM, just a few mouse clicks are needed to lay the initial toolpaths over all the model’s surfaces. That provides CNCPMI two vital productivity gains. “First, we see the same model in CAM as we see in CAD, so we no longer have to recreate the geometry in CAM. Second, we no longer have to recreate the entire toolpath if a part is revised. We just reload the new or changed model in EdgeCAM and the toolpath is recreated automatically if the changes are not drastic.”

The previous CAM system at CNCPMI was an antiquated 3D wireframe package running on the MS-DOS operating system. “It was unable to import solid models and we were receiving more and more complex and modern CAD files from our customers. To program, we had to convert them back to wireframes.”

Backward conversions were bad enough, but “we could never be sure that the customer’s geometry was converted correctly so we had to spend a lot of time double-checking everything. On complicated jobs, double-checking accounted for up to half the total programming time and sometimes a lot more. Seeing a solid model of a part to be manufactured is so much better that just wireframes.”

Interoperability, a big step even beyond associativity, comes into play with engineering changes. “If a customer changes a design in the SolidWorks model, or sends a new model, EdgeCAM immediately prompts you to update the model. This kind of interoperability reduces the risk of a lot of costly mistakes,” such as wasting time working on an outdated version. Associativity and interoperability are two of the keys to the seamless integration of EdgeCAM with SolidWorks.

Visualization lets programmers see, way in advance, things like whether the work holding might possibly compromise a tolerance or a future operation. “Being able to visualize the part in various stages of cutting is absolutely essential on multi-axis machines. On low-quantity jobs with short delivery times, we no longer have the luxury of cutting a test part so we have to get it right the first time.” Many CNCPMI jobs are for just one piece. A big order now, say 1,000 parts, was once considered low volume.

Sample 3D Milling of an aerospace part.

Machining simulation shows programmers a solid three-dimensional, realistic simulation of parts, and verifies the machining sequences on the computer screen before the machines are set up. “We see on the PC monitor exactly what you're going to get on the machine. This helps us be more confident that our parts will come out good the first time and with no unexpected surprises. It’s another time saving tool for us.”

By being able to use the automatic and manual feature finder and operational programming functions in EdgeCAM, generating complex code for our machines has become a lot easier. “The design to completely machined part cycle has been significantly reduced, in many cases by as much as half.”

Multi-axis and multi-plane programming ability are especially helpful when machining complex parts. “We sometimes use a rotary tool to do radial work, and then we can index it for axial work or index it to a virtual plane using the B-axis and coordinate conversion functions. This lets us eliminate the need for a lot of extra tools for chamfering, reduces the tool change time and cutting tool cost. Now we just index the C or B axis to a 45-degree angle and chamfer with a regular end mill.

“The multi-axis and multi-plane capabilities of our machines and CAM software also make hard-to-program, complex 3D surfaces a lot easier. We are definitely a few big steps ahead of where we were before we had multi-axis and multi-plane machines and programming capabilities. Programming complex functions has become so much easier.”

EdgeCAM Strategy Manager “offers us something unique, the ability to store and save for future use the engineers’ design ‘personalities,’ tool path preferences and know-how of the programmers. Reapplying good machining strategies to future parts eliminates a lot of guesswork and saves a lot of time.”

Praise for Reseller Peak Solutions
CNCPMI’s CAM evaluation was thorough. “Before we bought EdgeCAM, for a period of about six months we evaluated several other packages that claimed to be able to handle our machines and needs.” Moga said. “They ranged from the ones that had no clue what multi-axis mill/turn was to one that came very close to EdgeCAM as far as being able to address all of our needs.

“The main determining factor in choosing EdgeCAM was the support we got from Peak Solutions, our local reseller,” he added. Paul Mott [Peak Solutions owner] and Deborah Cox [sales manager] spent many hours making sure all our questions were answered before we made a decision on investing in our future CAM system.

“We were able to generate good code and adjust our code generators for post-processing just two weeks after we installed EdgeCAM,” Moga said. “It was the easiest to learn and use, complex yet not complicated and again with great, great support.”

RESULTS: Finding Errors ASAP
These CAM features take on greater importance as CNCPMI takes on more complicated work. Those jobs are more profitable (less competition) “but they are also riskier,” Moga points out. “We all make mistakes, every programmer does.

“It was easy to find errors in simple parts, even with old wireframe CAM, but there are no simple parts anymore,” he pointed out. “It is very hard to find an error in a complicated part with wireframe CAM. The screen is so cluttered with lines, polylines and arcs.”

On a complex job, because of the intense programming and machining, an error can be much more costly. “And the longer it takes to find the error, the costlier it is to fix,” Moga added. “Simulation of tool paths is crucial to avoiding those errors.”

All by themselves, mill/turn operations reduce a lot of possibilities for error. “Mill/Turn programming helps us catch errors early in the machining stages, usually in operation one or two rather than operation four or five,” he continued. “Very quickly, you have the completed part to inspect against. You don’t have to rely on partial inspections in several phases. If you did, you might miss something until it’s too late.

“Mill/turn offers greater accuracy, too,” Moga pointed out, “because you are only holding or fixturing the part once or at the most twice” and there is no risk of losing tolerances in transferring a turned part to a milling machine. “Many of our parts have true-positioning requirements under 0.001 inch and tolerances in the tenths [as little as 0.0001 inch]. Old machine tools could not hold those tolerances.”

BENEFITS: More Revenue, Better Profit Margins
“By being able to integrate complex milling and turning on a single machine, we save a lot of setup time and fixturing,” Moga said. “Our parts are produced faster and more accurately and by just one operator. Complex mill/turn machines help make us more competitive and able to respond to our customers faster and better.

Very short runs and prototypes offer a rare opportunity to boost revenues and restore profit margins. “We purchased EdgeCAM mainly to be able to reduce programming time on the multitude of short runs and prototype parts that we were running, and we did,” he added. “The more complex the geometry and the more complicated the job’s operations, the more productive we are now.

“Because programming takes so much less time now and because it is more accurate and so much easier, we are going after more and more short runs and prototype work,” Moga summarized, “and that gives CNCPMI a very bright future.

“Thanks to EdgeCAM I am ahead on my production, things are running smooth and great here and allow me to work shorter hours and my customers are happy.” Moga is happy, too. “I love the business. It is very competitive but I don’t care about that. Contract machining has provided me with a good life and with EdgeCAM it is getting even better.”

FOR FURTHER INFORMATION

THE USER

CNC Precision Manufacturing Inc.

www.cncpm.com

EFORMATINET