Material handling systems need components capable of solving the critical issues linked to weight and to maintaining a continuous production flow. R+W can provide different solutions to the requirements of torque transmission and limitation such as metal bellows couplings, elastomer couplings and torque limiters: these components can compensate misalignments, dampen vibrations and shocks and so on.
by Stefano Vinto
Digitiziation of material handling operations is one of the steps in the path towards the smart factory. According to Cushman & Wakefield (*), at the end of the first term of 2018, warehouses for stockpiling and handling materials were the object of important investments,which increased by 25% with respect to the previous year. This, according to experts, is also due to the success of e-commerce and of distribution in general. Even bank transactions in Italy, which almost doubled during this period, are evidence of this growth. Systems which number and locate components, monitor the warehouse, standardize items, determine the size of lots, the quantity of orders, safety provision, labelling and automatic identification techniques such as barcodes and QR codes, are just a few of the systems requested to maintain a handling line in motion within an industrial plant. Material handling is a determining factor in the choice of the plant’s layout. The layout of an industrial plant, linked to the particular type of production, and handling systems of the materials concerned, may not be conceived as two distinct entities.
Costs linked to material handling
Material handling does not provide added value to the product but it increases its production costs and therefore the final costs. On average, the relevance of handling costs adds up to 50% of total management costs. In some industries, such as mining, this percentage may reach 90%, justifying the efforts aimed both at designing and managing better the relative plants. When designing a modern handling line, up to 500 different types of material handling systems may be considered. Ergonomic requirements evaluated during the design phase, determine costs, for instance, due to the introduction of hydraulic lifting systems or resorting to exoskeleton systems, as we shall see later.
Designing handling systems with efficiency and ergonomics in mind
Designing material handling systems generally involves considering two main aspects: the efficiency of the system and ergonomics. Regarding the former, fundamental elements to consider are: the material’s properties; the company’s headquarters’ characteristics and layout; production flow; costs; the nature of the production process; engineering factors and reliability. The most frequently used material handling systems may be grouped in two categories: fixed path systems and variable path systems. The former include conveyors, single-rail devices, slides and belt systems. An exception is provided by overhead cranes: although they operate on a limited action area, they do not have path constraints. The latter include industrial trucks, forklifts, mobile cranes. Let us consider them , one by one. In transporters, a correct choice of the kinematic coupling is essential as, depending on the types chosen, they may provide torsional rigidity properties. This is the case of continuous conveyor belts in the mining sector.
This requirement is not present in manual or gravity conveyors such as the one shown in Photo 1. Industrial trucks may be of the trans pallet type (with manual or electrical steering) or elevators (forklifts), Forklifts are generally characterized by a great flexibility, linked to the possibility of mounting several types of tools according to the material handling requirements.
Photo 2 shows an electrical type of forklift. Cranes and lifts allow the suspended handling of materials (for instance in the case of cranes and overhead cranes). Although the space for manoeuvring is limited they may be adapted to both intermittent and continuous productions. Containers, although they are static, are the object of a continuous research and development activity, both for functional purposes and regarding the choice of materials (mainly PP and HDPE, both of which may be recycled). Starting from pallets, which are increasingly improved in terms of scalability and ease of handling (using forklifts or steered transpallets), pallet boxes have suitable properties of structural resistance for their stackability, besides being foldable. Finally, robots used in material handling do not just extend the functions provided by transpallets, forklifts and elevators (such as, palletizing robots) but they also improve the flow of material in the production line integrating with the transporters.
Starting from AGV systems (self-driving material handling vehicles) we reached the concept of mobile autonomous robots which combine the fictions of cobots (collaborative robots) with the smart management of material handling.
The opening picture shows a solution used by KUKA, where a collaborative robot is mounted on a platform with a laser guide system, which allows t to navigate quite autonomously. The platform also includes Mecanum wheels, which provide it with the maximum agility and user-friendliness, fundamental properties for an optimal use in those companies which respond to the requisites of Industry 4.0.
But collaborative robotics is not the last horizon for the industry’s evolution, The adaptation of the construction schemes of exoskeletons used in rehabilitation to mansions with high risk levels deriving from Cumulative Trauma Disorder (due to lifting and using heavy and vibrating equipment) determined the proposal of very interesting solutions An evident case is given by the partnership between Ekso Bionics and Ford Motor Company, which led to the production EksoVest, an exoskeleton system which provides support to the lifting of up to 67N per arm (Photo 3).
The role of the components supplier
Such a complex activity as the design of material handling systems finds a valid support in the suppliers of components.
This is the case with R+W, leading manufacturer of couplings and line shafts, capable of placing their experience at the designer’s service. Where material handling includes critical issues linked to the weight and maintenance of the continuous flow of production, R+W can provide a solution for all torque transmission and limitation demands, such as metal bellows coupling, elastomer couplings and torque limiters. BX metal bellows couplings for high torque values are torsionally rigid and backlash-free. Their design is simple and compact, they are easy to assemble and disassemble and are efficient in compensating misalignments. They are available in different lengths. EK elastomer couplings combine high flexibility and good resistance. They dampen vibrations and compensate shaft misalignments.
May elements influence the design of elastomer couplings: such factors as load, starting and temperature affect the insert’s life span. The elastomer element is available in different shore hardness levels, to provide a balance between vibration damping properties, torsional rigidity and misalignment correction for the best part of applications. ST torque limiters combine precision and strength. The ST1 model with key clamping, simple and compact, is torsionally rigid and equipped with an integrated bearing for loads deriving from pulleys or sprockets.
The STR model, in high-strength tempered steel, has a burnished surface protection. The motor part includes the coupling’s hub with key connection (and grooved profile if required) while the driven part includes the connection flange with fixing thread and integrated bearings.
The command modules on the perimeter may be regulated within the predefined range values. R+W Italia is an ideal business partner supplying couplings, line shafts and torque limiters, both standard versions and special solutions developed upon clients’ specific requests with the aim of providing the ideal coupling for every application; the vast product range includes solutions for every requirement. For additional information… look no further: register for R+W’s newsletter and receive all the most interesting news concerning couplings!
Stefano Vinto is a freelance journalist and a FEM specialist.