New Central Blending System Offers Greater Accuracy, Flexibility

A brand-new approach to central blending promises to save processors money, speed changeover times, and improve flexibility compared with current machine-mounted and central-blending technologies. Called BlendSave, the technology holds out the promise to impact central blending in the same fashion as central drying influenced that process. It is said to be suitable to processors of all kinds and is particularly beneficial to those that do frequent job changes that require recipe adjustments. Since the system requires less in the way of operator attention to make recipe changes and cleanups, BlendSave is also billed as ideal for processors with clean rooms.
 

BlendSave technology is available from a somewhat surprising source: Ampacet, a global masterbatch supplier. It is available by virtue of Ampacet’s 2019 purchase of LIAD Weighing and Control Systems of Israel. Ampacet has set up a new unit called CISystems to market the LIAD products worldwide. “We saw LIAD’s ColorSave series of loss-in-weight feeders and BlendSave central systems, and were tremendously impressed with the ability of these technologies to redefine masterbatch feeding and resin blending,” notes Doug Brownfield, commercial director of CISystems group. “We saw BlendSave as a revolutionary concept that would reshape the future of multiple-ingredient blending for all plastics processors.”

Long-time auxiliary-equipment expert Chuck Thiele is working with Ampacet to help further develop and market the technology. Thiele is perhaps best known for a 14-yr stint as president and CEO of auxiliary equipment supplier Motan. He is currently president and owner of Vactec LLC, which mainly provides consulting services for equipment suppliers and processors in the areas of drying, conveying, and blending.

Ampacet maintains that multiple-ingredient, gravimetric blending technology hasn’t changed much since it was pioneered in the late 1980s. Virtually all such systems deployed by processors nowadays consist of multiple collection hoppers, one for each raw material; a metering device at the outlet of each hopper, which may be a slide gate, vibratory feeder or screw feeder, depending on material and accuracy desired; a single weigh-scale hopper with one or two load cells that collects all ingredients at proper ratios to form a complete recipe; a mixing chamber for blending as many as three batches to homogenize and “smooth out” batch-to-batch inaccuracies; a collection-distribution hopper that feeds the processing machine; and a control system to manage feed devices and control the entire process. The BlendSave system weighs each ingredient in parallel, ensuring accuracy of the single batch.

Batch blenders typically have  been furnished in two configurations: dedicated/machine-mounted or central/remote-mounted. Ampacet notes that machine-mounted systems are supplied with mezzanines, which it says can add thousands to the cost of each system. According to the company, a $14,000, four-component blender can end up at with a price tag of $20,000 when the prices of vacuum-loading receivers and mezzanines are calculated. 

Thiele elaborates, “There is also lost production time for material changes. Typically, the operator climbs on the mezzanine and empties the feed hoppers of residual material, discards the material, cleans the hoppers, scale, and mixer. Then the hoppers have to be refilled with new material. A complete changeover can take two to three hours. Do the math: at 2 hr and $75/hr machine time with two changes/week, over 50 weeks it adds up to $15,000 yr, plus 200 man-hr. This is per machine, per year.” Thiele also notes that weighing multiple ingredients on one scale is subject to variations in accuracy, which is why many blenders must homogenize multiple batches before feeding the molding or extrusion machine.

Central blending systems, thought to be a good option to reduce costs, tend to be prone to material-segregation issues, Thiele says. “Segregation occurs when a centrally blended batch is vacuum conveyed to the machine,” he explains. “The problem is magnified when a single unit serves the same recipe to multiple machines and the blend goes through a material manifold. Because one blender serves multiple machines, there is less flexibility. On the matter of cost, in a setup consisting of 10, four-component blenders feeding 10 machines, you might need up to 50 vacuum receivers and two or more vacuum systems. That adds to the complexity of the system and can create uptime and operating problems. Changing to a new recipe requires the same manpower and time as machine-mounted blenders.”

BlendSave is a two-part blending process that has a Recipe Control Center (RCC) that weighs and collects recipes in a central location tied to a user’s ERP system, together with a dedicated combination vacuum receiver/mixer at the machine to mix the recipe (patent pending). The RCC consists of a number of weigh-scale feed hoppers and accompanying scale hoppers. Each scale hopper is dedicated to a single material, and the RCC may have as many as 30 scale-hopper sets, depending on the ingredient and recipe requirements of the facility.

The individual ingredients for a recipe are weighed simultaneously and discharged into a collection hopper. The outlet of the collection hopper is connected to a distributor system, which delivers the recipe to a specific buffer hopper. Each buffer hopper is assigned to a vacuum receiver/mixer at a specific machine. A vacuum-conveying system with a dedicated material line transports the individual recipe from the buffer to the receiver/mixer. The recipe remains completely isolated from weighing to mixing and delivery to the machine. Segregation reportedly is not an issue.

How it Works

The BlendSave centralized blending system accommodates up to 40 individual weighing chambers, fed directly from silos or containers, and can serve up to 50 processing machines with a potential throughput of up to 6 tons/hr. Each of the 40 weighing chambers can be configured as a 3 to 20 liter batch weighing chamber. Weighing in parallel allows for the use of smaller load cells, affording superior batch accuracy at greater throughputs, says Ampacet. BlendSave can provide consistent and high-resolution weighing channel accuracy, by individually weighing both major and minor ingredients.

 “As a plant grows, BlendSave can grow with it.”

The system is configured to weigh raw materials simultaneously and accurately, combining them as a batch according to a predetermined recipe destined for predetermined processing machines. Each batch is then distributed via a rotating-arm dispenser to its own buffer, comprising up to 50 buffer bins, with each buffer linked to one dedicated processing machine. Once a signal is received from a mixer/blender located at the inlet of the processing machine, material from the linked buffer is transferred via a delivery pipe to the mixer. The volume within a buffer bin and that of the linked mixer is adjusted so that the second can accommodate the first, producing what Ampacet says is exceptional batch uniformity. Blending in-line prevents the risk of material segregation. The BlendSave in-line vacuum/receiver/blender is filterless, which means no cleaning is required.

“With highly precise, dedicated weighing chambers that eradicate the risk of cross-contamination, BlendSave offers a unique solution that eliminates many manufacturing challenges when working with a variety of resins, recycled plastics (regrind and PCR resins) and other types of raw materials such as compounds and additives,” says Brownfield. “Depending on the number of masterbatches (additives and/or colors), they can be dispensed either via the BlendSave or by integrating a single-component gravimetric feeder. To that end, Ampacet offers the LIAD Smart ColorSave 1000 precision dosing unit, which provides significant savings in the cost of additives.”

The BlendSave system is modular, allowing configurations that can service two to 50 processing machines. Brownfield notes, “As a plant grows, BlendSave can grow with it. BlendSave provides full monitoring and control of customized job status, batch auditing, historical graphs and performance reports for each machine and job via an interactive PC dashboard or by linking BlendSave to a factory’s ERP platform.”

Brownfield adds, “The convergence of Industry 4.0 is leading the charge towards the development of smarter and more efficient factories. BlendSave allows manufacturers to improve their efficiency by simplifying and streamlining the workflow process, resulting in faster production of materials with greater quality control. The result is new opportunities for business growth through automation.”

Thiele provides the following example of ROI: “Let’s assume a 10-machine plant with typical four-component, machine-mounted blenders that formulate recipes from 16 different ingredients. Each blender changes material two times a week and an hour of machine time is valued at $75/ hr.

“The blender is going to be in the $15,000 range. To that you have to add an access and cleanout mezzanine at about $1500, and four machine loaders at about $1250. That brings the cost per station to $21,500, more or less.
“A 16-material BlendSave system serving 10 machines is going be right around the same price, maybe a little less, but if you assume a scenario of 1000 total material changes per year (two/week × 10 machines × 50 weeks) and the $75/hr machine time, plus labor to change material, the BlendSave gives the processor a ‘pay-for-itself’ benefit of more than $70,000/yr.”