Mistakes on the shop floor can be expensive, and it is critical that the machine operator and numeric control (NC) programmer communicate effectively. The implications of poor communication go well beyond wasted programmer and machine time. Something as simple as a poorly defined set-up instruction sheet can result in scrapped parts, broken cutters, or a damaged machine. Worse yet, a late delivery can result in the loss of future business. When all of these risks are combined, it’s difficult to quantify the value of good communication.
There are many benefits of accurate and detailed shop reports, which can be supplied in either physical or digital formats. In addition to avoiding the costly risks already mentioned, good reports increase operator confidence, requiring less babysitting of the NC machine, and less reason to turn down the feed rate. Good reports improve communication and reduce production time by providing clear instructions. They can help to formalise what is already being done and provide timely information that accurately represents the real process across all departments. Good reports can also be provided to customers, helping to establish or maintain a positive reputation.
There are many ways machine shops currently create inspection instructions and other reports. Some machine shops create shop documentation using an Excel spreadsheet and screen captures from their CAD/CAM software. But many reports require an “in-process” model. Creating these models in a CAD system is a manual process that requires a certain degree of technical expertise and engineering time. Not only is it time-consuming, it is prone to error and redundant. Many machine shops are unaware that they can simply use their NC simulation software to automatically generate the necessary reports for them.
Many machine shops already rely on simulation to prevent costly mistakes from getting to the shop floor. By simulating the post-processed code (G-code), the NC programmer can spend less time visually proving out the data. Machining a part in a virtual environment is quite similar to setting up and running an actual prove-out on the machine tool. First, the user specifies the stock from which the part will be cut, either by entering dimensions into the software or using a CAD model. Then, after selecting cutting tools, the NC program is used to simulate the motion of the tool removing material from the stock. The programmer can watch the material removal process and see details of how each cut changes the shape of the part. This eliminates having to try to imagine how cuts from the current operation will affect subsequent operations.
During the cutting simulation, the software automatically detects problems such as fast feed errors, gouges and collisions that could potentially scrap the part, break the cutter, or crash the machine. If an error is discovered, the programmer easily identifies the offending NC program record by mouse clicking on the error. The problem can then be fixed in the CAM software so that an error-free NC program is sent to the machine.
Examination of the simulated cut part delves deeper into the verification process. Is the resulting part dimensionally accurate? Does it match the final desired shape? Detailed measurement tools enable the user to verify and document dimensions such as wall and floor thickness, hole diameters, corner radii, scallop heights, depth, gaps, distances, angles, volumes, etc. The software even allows the user to optionally highlight features, such as all planes on the same level. The user can also view and measure all tool collisions, even after subsequent machining operations have removed them from the screen.
Some verification software also provides the ability to automatically compare the as-cut part with the original design. By embedding the CAD design model inside the stock, the user can automatically compare the design to the in-process workpiece to reveal any differences such as gouges or excess material not removed by the machining processes. If there are any violations or features out of tolerance, a report will tell the NC programmer exactly where in the NC program the problem was caused.
NC simulation software is the key to automatically generating shop documents because an in-process model of the part is created during simulation. When a simulated model has been created from the actual geometric data from G-code, there is no need to create an in-process model in a CAD system. Creating shop documentation can be quick and easy to automate, thereby significantly reducing engineering time. For example, the NC programmer can see and report the part in the as-machined condition, as opposed to the direct net requirements. Reports can be created during roughing operations that leave stock material, and the operator can then see exactly how much, and where, material remains. These types of reports are very useful and appreciated by both the shop and quality assurance (QA).
There is an almost unlimited number of reports that can be automatically created using NC simulation software. The layout of each report is completely user-configurable with a simple user interface. Using information from the simulation session, pictures, operator instructions, and other information can be automatically generated and inserted into the report. No programming is required and the reports can be output in HTML or PDF format. For example, set-up sheets with dimensions can help operators ensure that each set-up is correct. And when working with multiple set-ups, it is very helpful when the set-up sheets show the in-process state of material.
The QA department can also benefit from reports generated from the NC program. A significant percentage of manufacturing time is spent inspecting the workpiece. The user can simply click on cut model features in the simulation to create in-process inspection sequence instructions. The software will automatically identify where and what to inspect.
For the ultimate reporting capability, Machine shops can now go beyond 2D reports by using a free 3D simulation reviewer.Previously an operator would need to visit the programming office to view a program being simulated. But now it is possible to create and save a “Reviewer” file at any point in a simulation session. The saved file can then be sent to the shop floor. By using a standalone reviewer, shop supervisors, technicians, machinists and machine operators can review a 3D machine simulation of the NC program without leaving the shop floor.
The 3D reviewer is a very powerful tool that also helps improve communication with customers, suppliers, and anyone else that can benefit from having access to a 3D simulation. The user can play the 3D simulation forward and backward to see material being removed or replaced. Error messages and NC program text is highlighted when a collision on the stock or fixture is selected. Cutting conditions and a tool path line display can be optionally shown. The user can rotate, pan and zoom and the cut stock can be measured using a variety of measurement tools.
The review files can also be displayed using a free iPad application downloaded from the Apple App store. Reviewer files are transferred to the Reviewer iPad App through iTunes, Dropbox for iPad App, or email. In addition to the 3D simulation, the user can embed traditional reports in PDF format that can be easily accessed from within the app.
Creating reports is a required process for any machine shop, and generating set-up sheets, in-process inspection instructions, and other documentation from simulated in-process machined features saves time and improves accuracy. Additionally, machine shops looking to cut down on paper reports are no longer limited to a 2D world. A 3D simulation review file can eliminate virtually any surprise, in a virtual world.
