The Cutting Edge of Raw Material Handling
The method in which factories choose to receive their raw materials is ubiquitous, where sacks are abandoned for rail or silos in expectations of achieving cost-savings, only to return to sacks when it’s determined that rail and silo delivery is far from cost-efficient.
An automated method of sack handling has gripped the attention of many companies by solving some of the most pressing labor, safety and efficiency challenges facing factories today, and may be the final word for manufacturers considering sack or silo.
The Cost of Handling Raw Materials
Raw material processing is much more than it’s cut out to be. In fact, the method in which factories receive and handle their raw materials plays a critical role in determining factory efficiency, worker satisfaction, quality control and overall plant profitability.
Across all markets and industries receiving and processing raw materials, from plastics and petrochemicals in China to food and pharmaceuticals in Europe, delivery options are essentially the same – 25k sack or a train/truck delivered silo.
Manual or Automated
As the cost of labor in different markets still varies widely, it is sometimes thought that low-wage markets would be less keen on factory automation. However, as China has become one of the most automated markets in the world, it is clear that there is a lot more to automation than just reducing labor costs.
When considering raw material processing, and sack delivery in particular, the obvious expense is manual labor, where multiple teams of workers lift and cut sacks over a hopper. Yet within this seemingly “simple” manual process, lies some of the largest risks and avoidable expenses facing factories today, including injury, contamination, raw material loss and overall factory efficiency.
According to government data, the most common triggers of employee injury are manual handling, sprains, tears, pain and lacerations - accounting for well over 50% of on the job injuries. When considering the monotonous and repetitive task of lifting heavy sacks with a knife in hand, it is easy to understand how these employees are at a high-risk for injury. And the cost implications of employee injury, especially in Western countries, can quickly reach prohibitive sums in both direct and indirect costs.
Worker’s compensation, medical and legal expenses and factory downtime are just some of the direct expenses, while accident investigation, implementing new safety protocols, training new employees, lower employee morale and absenteeism are some of the indirect costs that will likely be encountered.
In fact, due to the high risk of employee injury, governments have set guidelines for the maximum amount of weight that an employee may lift. It goes without saying that this limit is often times not followed, leaving the window open for the levy of significant fines on factories breaking the rules.
Keeping sack fragments from mixing with the raw material is crucial for quality control, and a matter of health in pharmaceuticals or food production. Cutting the sack too roughly can shred the edge, mixing bits of paper, plastic or jute fiber into the product as it pours out.
In addition to ingredient contamination, sack fragments can clog filters, block pumps or interfere with solubility. In baked products, sack residue becomes visible as burnt specks, while its presence can increase the number of units rejected by quality control, further raising production costs.
And even in the traditional method of sack emptying, the risk of contamination from sack shavings, broken knives, cigarette butts and other waste is enough to result in product rejects and the occasional machine downtime for sterilization.
Raw Material Loss
High-priced products like pigments, plastic granules or powdered chemicals are not free-flowing and can stick to the seams or corners of sacks. Industrial production lines must choose between sacrificing those valuable bits in the interest of speed, and taking valuable time to brush out each sack.
In a university study conducted on raw material loss at a plastics factory, the results pointed to a 3% loss on average. Assuming each sack of raw material cost $100, the company just threw out $3, and racked up an opportunity cost of around $12 by not producing more. And even if a factory is conscious of this issue, and manages to lower waste and spillage to .3%, multiply this number by several thousand sacks, and herein lies one of the well-known challenges of sack emptying.
To solve this problem, the industry has suggested a number of technological solutions for preventing raw material loss.
One semi-automatic solution cuts the sack, while leaving the emptying to be performed on the run. With this device, employees load each sack onto the moving conveyor belt, demonstrating the first disadvantage: the process still requires manual labor – and therefore requires more workers in order to not surpass government set lifting limits.
The conveyor brings the sack to an automatic cutter blade, which slices the sack open as it passes. However, sack emptying time is limited to the time required for the torn sack to be pulled across a 1.5 meter gap with a hopper placed beneath. Any material still clinging to the interior of the sack after it crosses this opening is lost - an average of 1%-2%.
A second automatic solution resembles a giant blender. It destroys the sack to release the contents, inevitably mixing pieces of sack with the raw material. Whatever problem was solved by speed is replaced by a new problem; filtering the raw material from the shredded waste.
Using a "tumble dryer" method, the mixture is spun with force against a cylinder with holes similar to a sieve. Some of the holes become plugged by sack fragments or pockets of clumped material, while tiny sack bits escape through other holes to contaminate the sifted product.
Raw material waste still averages around 2%, making this fully automatic process a costly one. While increasing the processing speed will only increase that loss – to as much as 3%.
Factory Efficiency -
Even in optimal working conditions and all safety measures being followed, there will always exist the limits by which humans are capable of operating. Under best case scenarios, a factory worker can be expected to lift and cut up to 60 sacks per hour. For large plants using manual labor, the reality is a lot of workers with a seemingly never-ending amount of sacks to be opened.
All of these factors ultimately effect a plant's costs, product quality and time-to-delivery.
Rail and Silo Delivery
Due to the challenges presented by manual sack emptying, and the shortcomings of the automated solutions suggested by industry, various bulk transport innovations have appeared, including gigantic sacks delivered in 30-ton containers, and bulk storage in 200-ton silos which enable raw materials to be added to a production process at a controlled, uninterrupted rate.
However, these innovations have been a mixed blessing.
While bulk packaging does reduce man hours, the potential savings are eroded by the cost of dedicated trucks or trains required to deliver the huge containers. These methods cannot haul anything on the return trip, and must therefore return to the supplier empty with the cost of wasted logistical resources passed on to the buyer.
Bulk storage, in addition to the considerable cost of each silo, runs the risk of disaster by mixing multiple deliveries of raw material: high-quality material topped by an "off spec" shipment can render the entire silo contents useless, triggering alarming losses in material and production time. For these reasons, it is estimated that only 8% of factories receive their raw materials in bulk transport.
The Market Trend: Back to the Sack
Companies which opted for bulk delivery have learned these lessons the hard way, and are returning to shipments of raw materials in small sacks of no more than 25 kg each. The ease of quality control, the cost-effective transport, and the simple storage requirements are further enhanced by the competitive pricing among a wider choice of suppliers.
Studies have shown that unit sacks of raw plastic materials are more cost-effective than bulk by 40 - 80 Euros per ton!
And for this reason, companies find themselves facing the same disadvantages that prompted the move toward bulk packaging in the first place.
Therefore, the ideal solution to bulk material handling remains in the realm of sacks, and a new fully automated product is delivering a novel solution:
- Full emptying of sack contents
- Eliminate risk of contamination
- Eliminate manual lifting and cutting
- Handles all sack types
- Disposes of empty sacks
LaborSave Robotic Technology
LaborSave is an automated sack cutting and emptying system that has proven itself at several hundred of the world’s largest and well-known plastic, food and chemical factories. LaborSave handles up to 1,300 sacks per hour, empties more than 99.99% of sack contents and eliminates manual lifting, cutting or risk of contamination.
Factories that have integrated LaborSave within their production line have experienced an increase in efficiency and profits, with a reduction in costs related to employee absenteeism, machine downtime and lost material.
Short of using a forklift to place a pallet of sacks on a conveyor belt, LaborSave is a fully automated sack cutting and emptying solution. With a loaded pallet of sacks within the system’s unloading chamber, metal grips grab the top layer of sacks and carry them over a set of blades which neatly slice the sacks in parallel lines; without producing sack shavings. The slit sacks are then shaken above a loading hopper for several seconds, ensuring maximum material emptying before discarding the sack in a bin and starting the process again for the next level of sacks.
- LaborSave handles most types of sacks: plastic, polypropylene, paper and burlap, ranging between 25 and 75 kg in weight.
- Most sack arrangements on a pallet can be handled automatically by the system, with inclinations of up to 25 cm.
- LaborSave is mobile, providing sack handling for all industrial environments, any location in the plant, 24 hours a day.
LaborSave is CE, UL, TUV & GOST approved, and is represented worldwide by dedicated distributors.
Article Contact: 3 Towers Media