5 Things I Learned: At Pack Expo International 2016 Trade Show

Electric End-of-Arm Grippers

Robotics has entered many facets of manufacturing, including food processing and packaging.

There are many applications where traditional compressed air grippers are not appropriate – especially those where compressed air may cause contamination.

Enter the electric gripper.

Several manufacturers (SMC USA, Festo, Destaco, IAI America, Gimatic USA, etc.) have developed angular and parallel grippers using a servo motor to drive a slide screw which moves a lever assembly.

The lever assembly opens and closes linear-guided fingers (two or three finger configurations). These fingers can grip the interior or exterior of the product being picked up and can generate more than 200 N (45 lb_f) of grip strength.

To sum up, these electric grippers provide the following advantages over pneumatic grippers:

• They can control the position of the fingers. Using an encoder on the motor the fingers can travel to any position along the guide whereas a pneumatic gripper must travel its full stroke.
• They can detect grip. The controller uses the encoder’s feedback to detect if the part has been gripped and picked up.
• Their speed and grip force can be adjusted. Controlling the current to the motor controls the speed and torque translating into speed and grip strength of the fingers.

Formed Steel Tubing Machine Frames

Traditionally, large machine frames are created by welding heavy steel members with hard, right angle appearances. However, some machine manufacturers are turning to formed tubing/pipe frames to soften the machine’s look while maintaining its strength.

The round form softens the edge and reduces the surface ledges where debris can accumulate. In some instances, the tube/pipe needs to be larger to provide the strength, but forming the tubing can be less expensive than welding multiple angular pieces together to form the same basic shape.

Better Mounting Ideas for Large Capacity Delta Robots

If you are not familiar with the generic term delta robot, it is one in which there are three arms connected to universal joints at the base.

The six degrees of freedom: forward/back, up/down, left/right, pitch, yaw, roll

They are used to pick up objects and place them in another location quickly. Large capacity delta robots can move payloads (weight of object plus any end effector) up to 8 kg (18 lbs) with movement forces greater than 500 N (110 lb_f) in the X-Y plane and up to 1500 N (337 lb_f) in the Z direction. The forces translate into torque around each axis and approach 450 N-m (330 lb-ft). These forces and moments must be taken into account when designing the frame and its mounting members.

Some companies mount the robots to thick solid plates the size of the robot cage to increase the stiffness of the entire frame. However, if the frame is properly designed to handle the forces and moments, then the mounting members can be designed to handle the robot’s weight and the shear movement of the fasteners.

Most of the integrators showing these robots had open tops to allow for maintenance access to the robot base and relatively small mounting tabs welded to the frame. These companies showed — without explicitly revealing — the “openness” of their robot workstations.

A major benefit of open space in the workstation — especially in a processing or packaging facility — is ease of cleaning and maintenance.

Questionable ANSI Z535 Safety Labels

In the United States, machine safety is governed by law through the Occupational Safety and Health Act of 1970. It explains the requirements manufacturers and users must follow to keep the users safe at work. However, the Act defers to others to write and maintain standards to further guide manufacturers and users in all aspects of plant and machine safety, including safety tags. The American National Standards Institute (ANSI) Z535 standards describe the appropriate colors, signal words, safety symbols, and safety messages used in the facility, on machines, and in product manuals. Signal words and colors are combined to provide ample warning to the hazard. The table shown below shows the use of color and signal words for the most injurious hazards.

This table shows what to use if the most credible severity is a minor or moderate injury.

This table shows what to use when there is no risk of physical injury.

With all of the companies making ANSI certified labels to meet these specifications, why are manufacturers attempting to make labels that don’t conform?

Using a label such as the one on the left doesn’t provide sufficient information about the hazard.

The signal word text size is entirely too small to give the user/operator appropriate time to leave in case of a hazardous event. It is also not surrounded by its appropriate color – orange.

Even though the safety label below complies with ANSI standards, the CE insignia would show that this manufacturer should have been following ISO 3864 regarding the words and languages. The EU requires a warning tag to have any words presented in the language of the end destination, or provide no words at all to remove any confusion.

Safety Switches with Radio Frequency Identification (RFID)

Non-contact interlock switches have been available for quite some time. They’re used in applications requiring high hygienic standards or where extremely dirty conditions can occur.

Some switches use coded magnets to provide unique recognition. However, a misalignment between the magnet and the switch of just 4 mm (3/16 in.) can cause the switch to believe the guard is not in place. By incorporating RFID technology into the switches, adds a level of safety through complex coding and proximity sensing resulting in less false open readings.