We have completed a storage & weighing system for Saint Gobain Abrasives, at Stafford. The system is designed to dispense abrasive grits from 120 hoppers and deliver them to six mixers.

Saint Gobain are world leaders in abrasive wheel production. When they reorganised their production facility at Stafford (Formerly Universal Grinding Wheel Company) they needed to re-locate the abrasive grit dispensing system. This operation had been done manually and while re-locating the process it was decided to automate it.

The requirement was to dispense 135 batches in one shift. Any batch would pick upto 8 grits from any one of 120 bins. Any one grit might be required in quantities from 300grams to 250kg weighed into boxes with either a 30kg or 250kg capacity. A batch “ticket” had to be printed and put in each box. The box would then be delivered to one of six mixers. The daily production plan was to be downloaded from the company AS400 system. The batching system also had to keep stock records of the grits. No cross contamination was allowed.

The solution is a nest of 120 bins (40 off 1200kg and 80 off 600kg) each with a spout with a “clam shell” outlet valve. A travelling weigher passes underneath carrying the “box” on the scale. A hydraulic actuator opens the required valve to feed grit to the box. The amount the actuator opens the clam shell valve controls the rate of flow

The travelling weigher incorporates the following features.

• Motorised travel + speed control
• Binary positioning system (49 locations)
• 250kg scale + motorised rollers
• 7.5kg scale + tip action into box
• Conical “shield” to guide grit into 30kg box
• Hydraulic valve actuator with 4-20ma control
• Actuator location system (3 per binary location)
• Ticket printer
• Rolling cable guide with electrical and pneumatic connections.

The travelling weigher performs the following functions:

• Collects a 30kg or 250kg box
• Inserts the shield for a 30kg box (if required)
• Travels to the bin locations
• At each location positions the actuator under 1 of 3 spouts.
• Introduces the 7.5kg weigher or weighs direct to the box.
• Prints the batch ticket
• Delivers the box to 1 of 6 outfeed roller conveyors.