Material Handling & Feeding Systems by K-Tron

Auxiliary equipment takes in a broad range of functions, from materials preparation to post-mold finishing.

There will be an extraordinary range of new auxiliary equipment on display at the show.

Stefan Kalt recently joined K-Tron as Global Business Development Manager Plastic Compounding & Extrusion.

Jaime Gómez is the Global Business Development Manager for Chemicals and Plastics for K-Tron.

4.3.1.2 – Elements and Operation Schematic 4.3.1.3 – Photo (upper right)PrincipleIn loss-in-weight feeding, the entire feeder, hopper and material are continuously weighed.

4.3.2.2 – Photo (upper right) 4.3.2.3 – Perturbation Control Art 4.3.2.4 – Refill Control Art 4.3.2.5 – Pulsing Control ArtThe basic loss-in-weight operating principle requires that special enhancements to its control scheme be made if it is to be successfully applied in practice.

4.3.3.2 – Elements and Operation Schematic 4.3.3.3 – Photo (upper right)PrincipleA weigh-belt feeder primarily consists of a short belt-type conveyor that moves the material from inlet to discharge.

4.3.4.2 – Photo 4.3.4.3 – AutoTare Art 4.3.4.4 – Transport Lag Art 4.3.4.5 – Belt Slip ArtThe basic weigh belt operating principle requires that special enhancements to its control scheme be made if it is to be successfully applied in practice.

4.3.5.2 – Elements and Operation Schematic 4.3.5.3 – Photo 4.3.5.4 – SFM Equation w/SchematicPrincipleMostly encountered in primary resin compounding where throughputs are high, the combination of rotary valve and a gravimetric solids flow meter offers a simplified alternative to the use of a weigh-belt feeder in controlling base resin (fluff) feed rate for the proportioning of additives prior to pelletization.

The design and construction of a PVC compounding and extrusion plant is a complex engineering project, which can range from a simple inquiry for a plant expansion or modification to the construction of a new facility.

(Download this article for off-line reading)Unheralded as it may be, specwriting is the foundation of a successful feeding system.

4.8.2.2 – Recipe Effect Art 4.8.2.3 – ABC Example Art(Download this article for off-line reading)Much of the mountain of plastic products available in today’s global marketplace could not be manufactured, produced or formulated without the involve¬ment of continuous processing techniques.

4.8.3.1 – Photo 4.8.3.2 – Service Life Cycle Art(Download this article for off-line reading)Problem prevention is the first line of maintenance defense, and repairs are the rear line reinforcements.

4.9.1.2 – Photo/Graphic TBDAs a major contributor to formulation quality and consistency, feeder performance rightly deserves close attention and concern.

4.10.1.2 – PhotoFaced with several alternatives, making any rational purchase decision simply means making the best possible selection at the time it has to be made.Often what makes capital equipment purchase decisions so challenging is not just the complexity of the particular issues involved or the underlying mechanics of decisionmaking, but all the residual uncertainties of fact and assumption that linger even after months of careful investigation, evaluation and consideration.“Did we include all the factors that should go into this decision?”… “Did we account for them fairly?”… “Did we accurately estimate projected costs and savings?”… “Should we do more before we decide?”… these and other questions reflect the nagging doubts that confront any equipment buyer.While uncertainties will always exist, working within a logical and comprehensive decision framework will help assure the firmest possible footing in navigating the purchase process.

4.10.1.2 – Photo 4.10.1.3 – Quality & Efficiency ContributorsBecause of the uncertainties and practical difficulties involved in performing a rigorous pre-purchase estimates of Total Cost of Ownership (TCO), a less formal yet more practical approach may still provide the guidance needed to fairly support the purchase decision.

4.10.3.2 – Photo 4.10.3.3 – Quality ContributorsFactors contributing to the cost/benefit stream in direct proportion to process throughput include formulation accuracy and end product uniformity.

4.10.4.2 – Photo 4.10.4.3 – Efficiency ContributorsWhile the impact of quality-related cost factors are proportional to process throughput, efficiency contributors impose their costs or deliver their benefits over time by influencing process efficiency in various ways.

4.4.1.2 – Photo 4.4.1.3 – ArtThe widely used rotating single screw or auger is a familiar and straightforward approach.

4.4.2.2 – Photo 4.4.2.3 – ArtWhere the material’s handling characteristics are too challenging for one screw, two screws operating side by side often provide the needed solution whether for floodable or hard to flow materials.The basic twin screw design employs a pair of milled, concave-profile screws set 90o out of phase with each other so they fully intermesh.

4.4.3.2 – Photo 4.4.3.3 – Principle ArtBSP technology does not use the usual screws/augers, belts, pockets or vibratory trays to convey the material.

4.4.4.2 – Photo 4.4.4.3 – ArtBecause of ability to gently handle and move material, vibration may be a suitable strategy to control free-flowing, abrasive, friable and fibrous materials.

Whether performed automatically or manually, precise sampling is crucial to accurate performance measurement.

4.4.5.2 – Photo 4.4.5.3 – ArtIn bulk solids feeding, the familiar endless belt is known primarily for its central role in weigh belt feeding where an inlet gate shears material into a shallow bed prior to weighing and speed-controlled discharge.A belt feeder has relatively little innate material handling capability, though.

4.6.1.2 – Photo K Tron’s SmartConnex control architecture reflects the latest thinking in process plant control and communications technology.

4.6.2.2 – PhotoWith SmartConnex, each feeder has its own K Tron Control Module (KCM), usually mounted directly on the feeder.

4.4.6.2 – Photo 4.4.6.3 – ArtA properly configured, tapered cone, slowly rotating about its horizontal axis, can act to induce flow toward discharge at its narrow end.

4.6.3.2 – KSU-II Photo 4.6.3.3 – K-Vision Photo 4.6.3.4 – KSC PhotoSmartConnex offers a choice of three operator interfaces: KSU II Single Unit Display, K Vision Line Control Display, and KSC Smart Commander for multiple line control.

4.4.7.2 – Photo 4.4.7.3 – ArtRotating material halfway around a circle gives the rotary valve an advantage similar to the twin screw and Bulk Solids Pump approaches: that of capturing material in a confined space, moving it to another point, and discharging the load.Rotary valves, also referred to as rotary airlock feeders, rely on gravity to receive and discharge material.

4.4.8.2 – PhotoIn the context of application in the loss-in-weight feeding of critical liquids, slurries or pastes whose specific gravity varies sufficiently to warrant gravimetric flow control, a holding tank and pump or control valve replaces the standard hopper and metering device combination required in the feeding of solid materials.Because loss-in-weight feeding involves weighing the entire material containment and handling apparatus, the type of pump or control valve employed becomes irrelevant.

4.7.1.2 – Single Screw Photo(s)4.7.1.3 – Twin Screw Photo(s)4.7.1.4 – Bulk Solids Pump Photo(s)4.7.1.5 – Vibratory Photo(s)4.7.1.6 – Specialty Photo(s)4.7.1.7 – K4G Photo(s)Loss-in-Weight Feeders & BlendersUse K-Tron's modular Loss-in-Weight feeders for materials with varying bulk density and for material handling automation.

4.7.2.2 – Weigh Belt Photo(s)Weigh Belt FeedersUse weigh belt feeders for gravimetric feeding at higher feed rates or where low headroom is a problem.

4.6.4.2 – SchematicConnection between feeders and operator interface is via a network.

4.10.5.2 – PhotoTo the prospective feeding system buyer the purpose of Total Cost of Ownership analysis should be to direct and support decisionmaking.

4.5.1.2 – Photo 4.5.1.3 – Weighing Factors SchematicAccurate, precise and responsive gravimetric feed rate control is not possible without accurate, precise and responsive weight measurement.

4.5.2.2 – Photo (upper right) 4.5.2.3 – PDF: The Digital/Analog Debate (tbs) 4.5.2.4a – Vibrating Wire Principle Art 4.5.2.4b – SFT Photo Collage 4.5.2.5 – PDF: How K-Tron SFT Tech… (tbs) 4.5.2.6 – Strain Gauge Art 4.5.2.7 – LVDT ArtProfile of Vibrating Wire TechnologyVibrating wire weighing technology originated in the 1950s in heavy-duty mining, civil and hydrological load cell application where its reliability and drift-free performance was well suited to the need.

4.5.3.2 – Photo 4.5.3.3 – Suspension/Platform ArtThe need to accurately and continuously weigh in a process environment presents specific challenges to a loss-in-weight feeder.

4.5.4.2 – Photo 4.5.4.3 – Thru the Belt Schematic 4.5.4.4 – Auto Tare SchematicThe need to accurately and continuously weigh in a process environment presents specific challenges to a weigh belt feeder.

4.10.7.2 – Photo 4.10.7.3 – Tolerance vs Target Art 4.10.7.4 – Tolerance Art 4.10.7.5 – ExampleTraditional recipes, compounds or formulations are based on the notion of an ideal, targeted proportion for each component.

4.6.5.2 – Photo 4.6.5.3 - Schematic(4652 placeholder)Designed for use in profile extrusion, cast sheet, blown film, cable coating, laminating, precision tubing and pipe extrusion applications, K Tron's Continuous Gravimetric Extrusion Control package offers the ability to control extruder speed so that its output has a predictable and repeatable mass flow.

4.10.8.2 – FSD Promo Piece ArtProcessors wishing to automate the optimization of their recipes can download K-Tron’s free FeedSmart at www.ktron.com/cutcosts.

4.7.3.2 – SFM Photo(s)Smart Flow MetersUse K-Tron’s Smart Flow Meters for metering, monitoring or totalization of bulk material flows, or as a feeder in high rate applications.

4.5.5.2 – PhotoThe need to accurately and continuously weigh in a process environment presents specific challenges to a weigh meter / rotary valve feeder.

4.4.9.2 – Photo 4.4.9.3 – ChartTo assure a consistent, reliable flow through the supply hopper and into the feeder’s metering element, hopper agitation or other flow aid strategies may be required, depending on material.Proper bin design, the first step in promoting flow and avoiding potential difficulties, can be augmented by other, optional or add-on solutions including bin activators/dischargers, mechanical agitators, flexible hopper liners, air pads, injectors and blasters, hopper vibrators, and polished and coated hoppers.

Proportioning ingredients by the batch method is the simplest, oldest and most straightforward approach to formulating a plastics recipe.

4.3.6.2 – PhotoBypass ChannelA bypass channel allows the meter to be tared at any time during the measurement process.

4.3.8.2 – Elements and Operation Schematic 4.3.8.3 – PhotoPrimarily applied in compounding and extrusion processes, continuous on-line blending offers flexible, efficient, and highly accurate proportioning of all ingredients directly at the extruder inlet in both flood-fed and starve-fed applications.Unlike batch blending, continuous blending necessarily involves proportioning all components in one way or another, whether introduced as a single, dedicated ingredient (resin, filler, etc.), as a composite masterbatch pellet (pre-proportioned minor components in a resin carrier), or the downstream introduction of another recipe component through the extruder barrel).Illustrated here is a typical continuous on-line blending configuration:(4382 placeholder)In this approach several gravimetric feeders (usually loss-in-weight) are clustered above the extruder inlet to simultaneously introduce ingredients, each at a rate determined by its assigned proportion of total blend throughput.

4.2.1.2 – Vol/Grav Art In the continuous formulation of plastics the primary purpose of feed rate control is to achieve consistently accurate proportioning of recipe components (resin and required additives) prior to pelletization (in compounding) or end-product forming operations.Feeders produce a precise and controllable discharge rate for the material they are designed to handle.

All gravimetric feeders, regardless of type or operating principle, must meet three core requirements, here represented as the three sides of a triangle. (4222 placeholder)• Material Handling: Condition the material to minimize density variation (as required), and then produce a volumetrically uniform discharge stream• Weighing: Continuously perform accurate, high-resolution weight measurements to form the basis for subsequent control actions• Control: Continually determine and execute appropriate control actions to achieve or maintain the required gravimetric discharge rateEach side of the feeding triangle presents its own unique array of challenges, and each dynamically interacts with the other two.

Basically, there are only two main approaches to ingredient proportioning or blending: batch and continuous.In batch blending, required quantities of each ingredient are weighed out either manually or by automated batching systems according to desired batch size and recipe proportions.

4.9.2.2 – RepeatabilityRepeatabilityThe performance statistic most familiar to feeder users, repeatability quantifies the degree to which a feeder’s discharge stream varies over brief time intervals, producing a snapshot of one dimension of feeder performance.Note that the repeatability measurement says nothing at all about whether the feeder is delivering, on the average, the targeted rate (that is the purpose of the linearity measure performed on a properly spanned feeder). Repeatability does, however, reveal a great deal about the expected extent of short-term flow-rate inconsistencies, an important contributor to the integrity of the formulation and end-product quality.The repeatability measurement is performed by taking a series (usually at least 30) of carefully timed consecutive catch samples from the discharge stream, weighing each, and then calculating the + standard deviation of sample weights expressed as a percentage of the mean value of the samples taken.

4.9.3.2 – Timescale GraphicAn issue of growing importance in the specification and measurement of feeder repeatability relates to catch sample duration.

4.9.4.2 – Linearity GraphicAssuming a properly spanned feeder (a calibration scaling process resulting in measured and requested feed rate being equal at a specified operating rate), a feeder’s linearity measurement quantifies how well it delivers, on the average, the targeted discharge rate throughout the feeder’s complete operating range.Perfect linearity is represented by a straight-line correspondence between the setpoint and measured average feed rate throughout the feeder’s specified turndown range from its design full-scale operating rate.(4942 placeholder)To perform a linearity measurement, several groups of timed catch samples must be taken from the feeder’s discharge stream.

4.9.5.2 – Stability GraphicA perfectly performing feeder is worth little if it can’t maintain its performance over the long haul.Historically, many factors contributed to performance drift such as feeder type, analog control and weigh systems, the feeder’s mechanical systems, maintenance, and the operating environment itself.

You may think you have a feeding issue when in reality your problem may be upstream.

Hillenbrand, Inc., Batesville, Ind., the holding company for Batesville Casket Co., a leader in funeral services products, has signed a definitive agreement to acquire K-Tron International, Pitman, N.J.

Visitors to the recent NPE 2009 show in Chicago were looking for materials handling equipment that could do more than dry, blend, or convey resins. It had to do those things while saving energy, providing faster and easier maintenance, speeding product changeovers, reducing labor cost, minimizing waste, and providing better value for money. The new products cited below addressed those needs and more.

A new hopper vibrating unit is said to prevent bridging and rat-holing of cohesive, hard-to-flow bulk materials in stainless-steel hoppers.

By accurately measuring material throughput, gravimetric extrusion control can compensate for material and process variations and provide more consistent end product quality.

The K-Tron Micro Cone feeder features a highly innovative screw-less feeding mechanism to accurately dose free flowing color, masterbatch or additives into a blending system or directly into the process screw of an extruder.

K-Tron Process Group, Pitman, N.J., has developed its first gravimetric extrusion controls, designed for durable applications like multilayer films or sheet for automotive use or wire and cable coatings, where the thickness of critical functional layers may have to be guaranteed.

A new model of Micro Cone low-rate feeder (volumetric or gravimetric) will be introduced at the K 2007 show in Dusseldorf in October by K-Tron Process Group, Pitman, N.J.

K-Tron International, Pitman, N.J., which recently acquired Premier Pneumatics, Salina, Kan., has extended the Premier Pneumatics brand to all of its pneumatic conveying products.

K-Tron International, Inc., Pitman, N.J., has acquired Premier Pneumatics, Inc., Salina, Kan., a supplier of pneumatic conveying and bulk-handling systems.

NPE 2006 held no revolutionary changes in dryers, blenders, feeders, loaders, or conveying controls, but widely adopted improvements make the newest models easier to use and maintain—and easier on the budget, too.

Dryers, feeders, blenders, loaders, metal detectors, level sensors, mechanical and pneumatic conveyors, silos, bins, pumps, filters, valves, box fillers, bag dumpers, and materials-handling control systems constitute one of the biggest categories of products on display at NPE.

Two new models have been added to the line of Bulk Solids Pump (BSP) feeders from K-Tron Process Group, Pitman, N.J.

K-Tron International, Inc., Pitman, N.J., has merged its Pneumatic Conveying Group and the Feeder Group to form the new K-Tron Process Group.

Three years after a fire destroyed most of its operation, Tex-Trude came back as a more productive extrusion business.

Auxiliary equipment is shrinking to catch up with a growing market for small precision parts. Dryers, loaders, blenders, grinders, and chillers have all dropped in size for accuracy and fast product changeovers.