UK’s Leading Leather Manufacturer Has Better Data, Better Results

PROJECT SUMMARY:

The project allows Scottish Leather Group to track rawhides through an intake fridge system, and categorizes these hides based on their food grade, weight, gender, origin and status to intelligently fill the fridge rails. An outfeed selection algorithm helps operators choose the best available hides for a given fridge outfeed job (i.e. lime processing, recirc, etc.).

The project utilizes two in-house custom-built modules to conquer challenges faced in functionality (client USB camera, and 2D/3D charting), and has built-in analysis and reporting tools for management users.

The goal of the project is to give SLG more useful information on the quality of their incoming product and to give better granularity for hide tracking, much earlier on in the processing of the product, in order to increase end product quality and reduce the defect rate.

PROBLEM:

Scottish Leather Group had very little storage for fresh rawhides before they’re processed, so the company embarked on a project to build an intake fridge system. The PLC can move hides to any of the 25 rails but cannot make decisions on which rail to use. Ignition with a database was required to make these decisions.

Other challenges included:

• How to track an individual hide or group of hides
• How to efficiently categorize hides for regulatory and other purposes
• How to inspect and take photographs of hides for supplier queries
• How to select the most appropriate hides for the next process

SOLUTION:

The solution was to utilize RFID tokens for the hooks that hold each hide. By associating the hide with an RFID token, SLG can detect and store information about a hide from initial entry until it leaves the fridge system. Processes further down the factory line can use the job information to see a hide’s journey.

The system has four RFID readers on the infeed, and four on the outfeed side. On the infeed, a hide must be stamped, inspected, weighed and then entered into the fridge. A script is triggered at each of these points to create/update a hide record as it progresses, with the rail intake script consulting the database to find the most appropriate rail to use for the categorization used. On the outfeed, a hook will always be seen at the outfeed weigh scales and the recirc RFID point, but only hides that are to be processed by a lime drum or to be salted for later use are seen at the final two RFID points.

Ignition’s SDK helps at the inspection point, where an operator can choose from five inspection quality questions and needs to be able to take photographs of the hide and store them for later reporting. This was achieved using a custom module built by SLG that allows the client to access a local USB camera; an IP camera was not suitable in this case. The operator just needs to press the capture button and the photograph is saved and assigned to that hide. Any number of photographs can be stored against each hide. It’s very intuitive.

At any point, a user can view the Rail Status page to see the rail location of each hide, along with an information view for each rail detailing each hide in the order they were entered.

When an outfeed job is created, an operator can choose to reject, reorder, drum process, or salt process a group of hides. When the operator starts a job, the system uses a set of unique algorithms to present the operator with a selection of hides that best match what they need, based on the stock available in the fridge. These algorithms must do/consider the following:

• Ignore matching hides that are behind incompatible hides on the same rail
• Always match the food category
• Match gender
• Match contract state
• Match the origin and weight categories, but allow for a mixture if stock levels don’t give an exact match
• Match quantity but with a tolerance if the available hides are slightly less than the number required
• If the quantity of hides doesn’t reach the required number, then do the above but by weight instead
• Not exceed a maximum weight, regardless of hide count requested

Ignition’s versatility and ability to allow users to easily manipulate databases made this possible. Other SCADA packages would have had real trouble with even some of the basic functionality necessary for this project.

Reorder jobs allow the operator to select an option to automatically suggest rails to reorder. This is an algorithm that looks at the current rails and chooses nearly empty and mixed rails to reorganize and unlock stock for easier selection. Mixed rails are only created when stock levels are high and no other option is available at intake.

Reject jobs record the outfeed weight of each hide, and then drop the hides into a reject bin.

Zip files of all photos and commercial documents associated with a delivery, and a spreadsheet of their hide data can be easily created in one action. This gives SLG a useful export for quality and compliance records. This, along with the 2D/3D charts available to them, showing current stock statuses help them utilize the fridge as much as possible.

DEPLOY DATE: April 2022