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Linear actuators enable faster delivery of prescription medication to patients

Highly automated storage, handling and retrieval systems for pharmaceuticals are utilising high precision linear actuators from Schaeffler to help speed up delivery times for prescription goods, whilst also expanding the range of products that a local pharmacy can offer patients.

Many of us are familiar with the typical scene at a high street pharmacist: the customer enters the store, hands over a prescription and waits while the staff fulfil the order. Unfortunately, the particular medication you require is often not in stock and so you are required to return in a few hours once the correct product has been delivered to the pharmacy. How this delivery is achieved so quickly involves complex logistics.

First, the pharmacist calls the pharmaceuticals supplier, who takes the order, checks the stock situation and searches to find the storage point where the required medication is located. The retrieval process is carried out and the correct order quantity picked. The remaining packages must then be returned to their pre-allocated location and correctly moved back into stock. The supplier places the picked goods into a container and at a defined time, the delivery van departs for the pharmacist. This process often takes just a few hours but is labour-intensive and the customer (patient) has to wait for their prescription or return to the dispensary some time later.

Pharmacy automatic storage and retrieval systems

Equipping a pharmacist with an automated storage & retrieval system is highly attractive as it would ensure maximum availability of prescription drugs resulting in increased sales potential and the opportunity for the pharmacy to expand its range of available products.

A machine builder based in Germany recently approached Schaeffler for help in developing such a system. The emphasis from the start of this partnership was, wherever possible, to use high performance, high quality standard mechanical components and drives that were readily available in the marketplace.

The automated storage system itself comprises racks with drawers for the pharmaceutical products; a three-axis linear robot with a gripper module for handling the products; a cycled conveyor belt for moving the products into the storage area; a contact light source for localisation of packages; cameras and scanners for identifying product and for determining package size; a conveyor installation with a pneumatic transport system; transport belt and goods delivery chute at the discharge point; a stock control system; and an installation controller and related software. The linear robot system is at the core of the installation, as this performs all movement tasks of products in and out of stock within the storage area.

Standard, modular components

In developing the three-axis linear robot, the customer's automation technicians worked in close partnership with experienced application engineers from Schaeffler. The design was achieved exclusively using standard driven linear and telescopic actuators from the Schaeffler range. The horizontal axis (x-axis) includes four MLF32 linear actuators with a track roller guidance system and toothed belt drive, installed in the base of the system (as a linear guidance axis) and at the top (in a design similar to a gantry axis). Between the upper and lower linear guidance axes is the vertical axis, which comprises four linear actuators with linear recirculating ball bearing and guideway assemblies (2 x MKUVE20-ZR and 2 x MKUVE20-ZR-OA units).

The vertical axis acts as a carrier for the MTKUSE25-ZS telescopic actuators, each of which is fitted with an arm and a vacuum suction gripper. This means the telescopic actuator needs to support the weight of the arm, vacuum suction gripper and the package, as well as providing secure transportation. This also applies to the vertical and horizontal axes, where travel and positioning accuracies of around 0.1mm are required. Further requirements include: accelerations of 5m/s2; maximum travel velocities of 2m/s; low noise and vibration; minimal maintenance requirements; simple design integration; easy, rapid mounting; and easy set up and commissioning. In addition, the linear actuators had to be compatible with other machine components and must guarantee long-term accuracy, as well as meeting the high performance requirements of the application without incurring excessive cost.

Driven linear actuators cut time and costs

Schaeffler linear actuators offered the machine builder a cost effective solution that also met the technical performance requirements. In addition, the use of robust, self-supporting linear actuators based on extruded, inherently rigid, aluminium profiles eliminated the need to design and construct costly gantry structures.

By developing an automated storage, handling and retrieval system, the customer was able to increase the capacity of its facility to 40,000 product items, while still retaining a storage footprint of around 16m_. The storage and retrieval system is amongst the most compact of its type currently available. Due to the high speed driven linear actuators from Schaeffler, the system is also amongst the most dynamic of its type on the market. The machine manufacturer relies completely on Schaeffler's knowledge and experience of linear motion technologies and is making considerable savings in terms of design, mechanical production, mounting and initial operation. Additional savings come from using linear actuators that are supplied ready for mounting. The machine builder can also request support at any time from Schaeffler's application engineers.

Schaeffler (UK) Ltd