A clever handling solution

“Extremely flexible”, “highly productive” – such attributes may sound suspicious when used to describe automation solutions. However, these terms are justified by the latest project implemented by Fastems Systems.

A machining company needed an automation solution for unmanned, highly flexible and complex machining of a wide range of workpiece sizes over a period of up to 72 hours. The company manufactures high quality, complicated and dimensionally accurate components, as well as individual and a limited-number-series of complex parts.

The solution is a robot cell. Or to be more precise: A DMG five-axis machining center serviced by a FANUC industrial robot, equipped with a servo gripper that can do far more than handle a diverse range of parts.

High precision gripper and space-saving parts store

The main components of the automation solution are the highly precise servo gripper that manages large strokes of up to 450 mm with variable gripping forces; a storage tower made by Modula for a variety of blank sizes, semi-finished parts and finished parts; a station for loading the workpieces into vises and clamping devices; the robot, with its six axes supplemented by two additional axes (for the servo gripper and the vise station); and the Fastwizard intuitive robot controller made by Fastems.

Extensive range of different workpieces in variable quantities

As opposed to a typical robot production cell, this solution provides greater flexibility for the complex machining of a large and diverse range of parts in variable quantities. This is apparent when one considers that the dimensions of the workpieces range between 40 and 250 mm (in width), 40 to 280 mm (in length) and 10 to 80 mm (in height), with a maximum blank weight of 32 kg.

Robot controller monitors incoming orders

The brains of this automation solution is the Fastems Fastwizard. Here’s how it works: The robot controller queries a customer network folder that holds orders filed as NC programs. As soon as a new NC program is filed in the network folder, Fastwizard accesses this program and uses it to generate a production order. The header file for the respective NC program is used to provide the controller with workpiece dimensions and other data. Fastwizard also uses parts management to locate where the blank to be machined is located in the storage tower.

Complete control over force and stroke

When a production process begins, the robot starts by removing a vise from the storage wall and then transports it to the vise station. Before loading the vise with a blank, the clamping jaws are blown off using an air jet.

The robot grips a blank taken from the storage tower, and places it in the clamping device at the vise station (vise), which is closed using the servo screw unit at the station. The length of the blank for machining and the stroke required is checked by means of the robot’s servo gripper and the vise station, which also regulate the force necessary to clamp and grip the respective workpiece. The width of the workpiece is checked using the vise, while a laser light barrier at the vise station is used to check the height of the workpiece.

Integrated turning station provides even greater flexibility

After it is properly clamped and checked, the robot loads the workpiece into the machine tool where machining begins as soon as the NC program is transferred from FastWizard to the machine’s control. When machining is completed, the robot removes the vise from the machine tool for unloading at the vise station, and the semi-finished part is stored in a predetermined position. If the workpiece requires further machining, it is transferred from the storage tower to a turning station. When the turning process is finished the workpiece is, again, picked up in a vise for machining of the sixth side.

Higher productivity using a second machining center

Figure showing servo gripper: The servo gripper, adjusted using a ball screw, with a variable gripping force of up to 8,000 N, provides high positioning accuracy and is designed for large strokes of up to 450 mm. The gripper checks the length of the workpiece together with the vise station.

This automation solution allows the company to realize complex production (machining up to six sides) of a large and diverse range of parts in variable quantities, unmanned for up to 72 hours (such as over weekends). Moreover, because the robot cell is equipped with two machining centers, two different production orders can be simultaneously processed in the future.

The intelligent handling provided by a servo gripper that handles both the workpieces and the clamping device, while also checking the length of the workpiece for the stroke, allows for extremely flexible, highly productive and, therefore, exceptionally economical production.