MMS Blog
By: Peter Zelinski 3. October 2018
10 Ways to Think Differently about Robotic Automation
The United Grinding Flexload module as seen at the end of a cylindrical grinding machine. The machine has been modified to allow the robot a more efficient means of access than the door the operator uses.
This autonomous vehicle found its way through a busy trade show booth to deliver parts from a robot-tended machine to robot-tended inspection. It could do the same thing in a production plant.
This robot isn’t fixed to the floor. It is mounted on a stable but movable platform that, in this case, includes drawers for the robot to reach into to store and retrieve parts. The system (from APT) makes the robot easily redeployable instead of being essentially dedicated.
Engineering robots for tight spaces involves snaking, intricate motions. According to MakerBot, engineers with Kuka proved out the motion for this robot by 3D printing prototypes of its different sections. Printing the pieces seen here took about 120 hours total.
Robots used to know their place. In the past, a robot would run behind a safety cage doing repetitive motions that rarely changed from week to week, let alone from day to day. Now it’s not so simple. Robots are, in many cases, easy to redeploy; collaborative robots (cobots) operate safely alongside people; and other advancing technologies seem to conspire with robots to make them even more effective. The result is an expanding scope of what robots might mean for manufacturing. Gathered over months from various events, discoveries, observations and conversations I’ve been party to recently, here are many glimpses of the changing nature of robots. Consider these points as a means of uncaging your own thinking about robotic automation, and perhaps even reconsidering what a robot might do for you:
1. Machine tool builders are adapting to robots. United Grinding’s Flexload, for example, is an add-on automation module by which the robot enters through one end of a grinding machine. The doors are still available for the operator, but for the sake of safety and temperature control, the robot’s access is different.
By: George Schuetz 2. October 2018
Less Is More with Dial Comparators
The dial comparator enables relatively high-resolution measurements without the cost of an electronic gage and without the risk of error associated with a dial indicator.
Most dial indicators have a total measurement range of at least 2.5 revolutions of the needle, as per American Gage Design (AGD) specifications. Additional range in the traditional indicator was useful many years ago, when machine tool accuracy demanded a broad measurement range to help machinists "creep up" on a specification. Now, gaging suppliers often recommend that an indicator be chosen so that the tolerance range for the parts being measured covers between one-tenth and one-quarter of a single needle revolution. This provides a large enough tolerance zone to read easily and leaves more than enough area on the dial to see what is out-of-tolerance. It is a rare occurrence when anyone actually bothers to read a gage if a part is more than a half revolution out of tolerance.
Two and a half revolutions are simply unnecessary for most comparative gaging applications, and sometimes they are a real liability. Considering how quickly the needle swings on an indicator, it is not surprising that machinists occasionally miss a revolution. On a standard dial indicator, a measurement that is a full revolution out-of-tolerance can appear to be exactly on specification to an operator who is distracted – or poorly trained, poorly supervised or hurried. Errors may occur through simple inattentiveness or an absolute misunderstanding of how to set up and master the gage.
By: Jedd Cole 1. October 2018
CAD/CAM Software Contributes to Shop's Fourfold Revenue Increase
This is the lower-jaw die holder for a custom, automotive stamping press. It started out as a 7-by-8-by-9-inch solid piece of pre-hardened 4140 steel.
Various 3D tool paths defined in Esprit are used to create the contours of the part. High-speed 3D milling minimized setups and non-value-added moving time by keeping the machine in the cut and enabling the machinist to tend to other responsibilities. Before using Esprit, the company would have needed to invest in custom tooling, with long lead times, to achieve some fo the finishes and complex geometries that were required. Instead, the company has simplified its tooling by using an Iscar indexable ballnose end mill for the vast majority of the material removal.
Pictured here are some of the team members from C&S Machine and Manufacturing in front of one of the shop’s 30 CNC machines. The machine behind them was the VMC that cut the parts pictured in the article. From left to right: general manager Ryan Steele, machinist apprentice Kyle Dunn, manufacturing engineer Mike Curry and operations manager Tom Grace.
Keep growing, and eventually there will be growing pains. This was the experience of C&S Machine & Manufacturing Corp., a machine shop based in Louisville, Kentucky. The need to make the programming process more efficient became crucial to winning bids, which led the shop to acquire Esprit software from DP Technology (Camarillo, California).
Far from its origin in a 180-square-foot shed in 1969, C&S Machine & Manufacturing Corp. has three buildings today with more than 60,000 square feet housing 30 CNC machines including vertical and horizontal machining centers as well as vertical and horizontal lathes with live tooling. The company also offers lasercutting, bending and welding services.
By: Eli Plaskett 30. September 2018
Five-Axis CNC Machining with an Angled Rotary Table
One of the most reliable ways machine tool builders maintain workpiece stability is to build a sturdy, heavy frame and a solid bed to reduce the miniscule movements during machining that can cause tool deflection or chatter. However, five-axis machines have a somewhat less-stable worktable design. This is because of the rotation they must provide to position part at different angles.
According to Makino, different five-axis configurations have different benefits and challenges to consider, being that tilting the worktable along the A or B axes can compromise rigidity. For example, at certain positions, a swinging trunnion table can introduce leverage that amplifies micro-movements in the workpiece when the cutting tool makes contact, possibly resulting in deflection and chatter. While this loss of rigidity can be frustrating, the benefits of the complex contouring and single-setup machining are often more than enough to justify the investment. However, Makino recently developed the D200Z, which it says is designed to eliminate the need for a compromise. The company displayed the machine at Amerimold 2018, where it demonstrated how the CNC vertical machining center (VMC) achieves five-axis movement through a set of two integral rotating tables, one of which is tilted at a 44.5-degree angle.
By: Timothy W. Simpson 29. September 2018
Machining Additively Manufactured Supports: The Tool’s Perspective
Figure 1a: In-plane milling forces during 10 rotations on fully dense material.
Figure 1b: In-plane milling forces during 10 rotations on thin-walled support structures.
Figure 2a: Moving averages for milling forces on fully dense material.
Figure 2b: Moving averages for milling forces on thin-walled support structures.
Last month, we dove into detail about machining away additively manufactured metallic support structures– the thin-walled structures that are used to anchor the part to the build plate and keep the part from warping and distorting during the build. We saw that supports maintained their structure and tended to collapse rather than uproot and cleanly shear away when milled. We also saw that the problem is further complicated by powder that can be trapped inside tall support structures. Even after blowing away loose powder with high-pressure air, un-melted powder feedstock can still be found, compacted inside taller support structures.
So, while we can machine away additively manufactured support structures—assuming we can access them with our machine tool—what do thin-walled support structures and hollow sections (that are sometimes filled with trapped powder) mean for the cutting tool?
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