One of the key drivers of profit involves optimizing the flow of products through the production line.
Fitting an in-line or over-line Automated Inspection System at one or more points helps determine non-conforming items based upon a customizable range of test criteria, and when paired with the right Automated Sorting Process, can increase throughput efficiency and improve the quality of your product.
These Automated Inspection Systems, such as the ones manufactured by EyePro System and Sightline Process Control brands, pair high-speed cameras with imaging software to identify and measure objects at full-line speeds.
This article highlights the sorting mechanisms frequently used for the production of processed food products, specifically outlining rejection and recirculation.
The intention is to aid manufacturing and operations personnel looking to implement a fully automated solution and know what options are available to the market and the main factors that should be taken into account when installing such systems.
When choosing the best sorting technology to integrate into an inspection system, there are several major considerations that should be taken into account when conducting an evaluation.
These include assessing the physical properties of the product for inspection, the speed (i.e., throughput) of the production line, the set-up of the production line, material handling requirements for the particular applications and compliance reporting requirements.
In some instances, the value of a rejected non-conforming item may advocate for re-processing rather than disposal of that item.
Consequently, item redirection systems can be utilized to re-route the product flagged for secondary inspection or further processing. An example of this would be a unit of poultry, which may fall short of the portion size requirement for processing as a frozen chicken breast, but may still be viable for use in breaded chicken nuggets if processed properly.
A product’s physical properties will determine the best sorting solutions suited to the specific application. For example, when handling comparatively small and lightweight baked goods such as buns or cookies, air jets can typically be installed above or to the side to isolate and reposition individual items with precision.
For larger items, such as a whole loaf of bread, a servo-driven paddle, pusher system, or other product-specific rejection systems will usually prove to be more effective. Size, weight, surface area, texture and dry vs. wet should always be considered.
The production line configuration will also have a significant impact on the rejection sorting method that should be applied. The surface texture, width, speed and physical constraints of the conveyor and surrounding environment are all key factors that must be considered.
For production lines that require routine cleaning, the inspection system will generally be delivered to conform to IP69K standards. It is crucial that the rejection sorting system also meet these environmental standards to ensure the combined system performs both reliably and safely.
The way that rejects are captured will be determined by the expected disposition of those products. If non-compliant goods are simply disposed of, then the main consideration will be the volume of the capture container, which will consequently be a function of the size of the product and the rates of rejection expected.
Another element to consider for disposal situations should be the accessibility and mobility of the capture bins. Depending on the installed inspection system, it may be feasible to create alerts for reject bin capacity to advise personnel to empty or replace when appropriate.
When a product shows signs of being suitable for reworking, a good number of the rejection methods stated below can aid in the redirection of appropriate products for manual inspection or to a secondary processing line.
When a vision inspection system is built in to the manufacturing process, sophisticated images and data associated with repurposed products offer manufacturers the ability to gain insight into process issues and trace the batches involving reworked ingredients.
Both inspection systems and the pre-configured software will generally have the capacity to control PLCs (Programmable Logic Controllers), which consequently are able to drive other elements of the manufacturing process, including automated rejection systems.
Once the inspection system has determined which item is non-compliant, the software will transmit an instruction to the PLC to activate the rejection system(s), which consequently removes the non-compliant item from the conveyor for disposal or in some cases, redirects the item to a secondary process.
The range of rejection systems available are far-reaching, and some would exceed the scope of this article. However, the task is to offer meaningful insight into the selection of rejection technologies that are frequently used.
Figure 1. Inspection System Integration with Reject Mechanism. Image Credit: KPM Analytics
For goods marked up for further inspection or alternative processing rather than simple rejection and disposal, it is usual to install and apply diverter mechanisms to transfer identified products to a secondary conveyor or capture system. These solutions are known as “divert” or “diverter” systems throughout the rest of this section.
In the most basic scenario, when the inspection system flags a non-conforming product, it will pause the conveyor belt and activate an alarm calling for production staff to review the product rejected and remove it manually from the production line as deemed necessary.
Air jet manifolds placed in close proximity to the inspection system offer a dynamic and reliable methodology for the rejection of products with greater surface area to weight or height to weight ratios.
Individual jet nozzle air blasts can accurately target singular items that are out of specification and pre-configured measurement criteria, even in multi-lane production lines.
Two of the main advantages of pneumatic rejection systems are that they can supply rapid response times and generally have no moving parts, thereby reducing maintenance to a bare minimum.
Examples of processed food products appropriate for air jet rejection include small to medium baked goods such as English muffins, plain round buns and even bagels:
Figure 2. Side View of Top Mounted Air Jet Rejector (single or multi-lane). Image Credit: KPM Analytics
Figure 3. Top View of Top Mounted Air Jet Rejector (single or multi-lane). Image Credit: KPM Analytics
Figure 4. Top View of Side Mounted Air Jet Rejector (single-lane). Image Credit: KPM Analytics
There are several conveyor “nosebar” rejection systems with the ability to drop, lift or retract a section of the conveyor for the purpose of rejecting or diverting non-conforming products.
Figure 5. Frozen pizza crust on a drop down paddle rejector conveyor. Image Credit: KPM Analytics
Figure 6. Side View of Lift Nose Rejector (single-lane). Image Credit: KPM Analytics
Figure 7. Side View of Retracting Nosebar Rejector (single-lane). Image Credit: KPM Analytics
Pusher rejectors are linear actuators that can operate under the guidance of pneumatic, hydraulic or electrical means. They are well-suited to single-lane production lines and larger products.
Push rejectors will quickly move the item flagged into a reject bin or, in some instances, pass it on to an alternate production lane while the compliant goods continue unimpeded down the line. Examples of processed food products well-suited to push rejectors include bread loaves or packaged goods.
Figure 8. Top View of Push Rejector (single-lane). Image Credit: KPM Analytics
Figure 9. Top View of Sweep Arm Rejector (single-lane). Image Credit: KPM Analytics
A sweep arm rejector can be set up to sweep across the line conveyor, pushing non-conforming products into a reject bin or passing it on to a secondary conveyor for re-processing.
Sweep arm rejectors are ideal for the processing of medium-weight goods in a single-lane production line. Examples of processed food products well-suited to sweep arm rejectors include meat products such as poultry, either raw, cooked or breaded, as well as tinned and packaged goods that may not be compliant with packaging and labeling inspection criteria.
Push finger rejectors function in a similar manner to sweep arm rejectors and are generally used for diverting applications. Push finger rejectors can reposition a product on a conveyor gradually and with minimal force, thereby directing it to a secondary inspection or processing line.
Figure 10. Top View of Push Finger Rejector (single-lane). Image Credit: KPM Analytics
To increase production throughput and quality, selecting the appropriate sorting solution to complement an automated inspection system is crucial. Taking into account the physical properties of the product for inspection, the configuration of the production line, and other material handling factors are key factors when making this decision.
Used in parallel with Over-Line and In-Line inspection systems, the software facilitates automatic rejection detection, which ensures that defective objects are removed before reaching the end customer.
Rejection limits can be configured and customized to allow decisions to be more predictable and repeatable. Detailed records of rejected products are stored in a database, which enables consistent, detailed reporting and data visualization via analytics.
EyePro System and Sightline Process Control – two members under the KPM Analytics family of product brands – are the leading providers of vision technologies in the food industry, supporting manufacturers by allowing them to implement quality control and production automation solutions.
These systems provide objective, meaningful and actionable measurements in a production environment at full-line speed.
Whether as a fully-integrated in-line system with process control or a benchtop unit, with vision technology systems, food manufacturers are able to see the benefits in cost savings, efficiency improvements, and product quality enhancements almost immediately.
This information has been sourced, reviewed and adapted from materials provided by KPM Analytics .
For more information on this source, please visit KPM Analytics .
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