Siemens Elektromotorenwerke (Bad Neustadt)

Published in: motion world 2008/01

Perfect Shafts

Electro-mechanical retrofitting ensures quality and optimizes maintenance processes in motor shaft processing

The Siemens plant for electric motors (EWN) in Bad Neustadt/Saale has – both in terms of electrics and mechanics – brought three proven, three-shift-operated manufacturing cells for motor shafts that are over 15 years old back into the 21st century, killing several birds with one stone in the process.

Retrofit from a single source: Sinumerik 840D and new drive technology get the quality and productivity of shaft production in the Bad Neustadt electric motors plant back on track
The first of these ensures long-term quality without extra costs and outlay. In addition, special software tools implemented in machine controls will enable condition-based planned maintenance that is more precise than ever before. This, in turn, will lead to higher availability and productivity in the long term. Machine handling has also become simpler and safer.
A growing number of problems …
…due to service requirements at two production cells at the same time have jeopardized EWN’s ability to deliver and meet deadlines. Also availability and functional scope of the discontinued CNC-controls no longer matched today’s expectations. The search for both a technically and economically sustainable solution quickly focused on a significantly more cost-efficient retrofit as opposed to purchasing new machinery.
Extensive retrofits from a single source
The solution with the best cost-performance ratio came from Siemens Nuremberg. As a general contractor, the retrofit specialists provide complete solutions covering both the entire electrics/electronics and mechanics.
To ensure that the impact on production capacity was not too severe, the three production cells at EWN were replaced one after another. The entire process took around four months. During this refit, recirculating ball spindles, guides, and turrets were all replaced, absolute value gauges/devices were installed, and clamping cylinders, tappet and gripper units were reconditioned. Using Sinumerik 840D powerline and coordinated drive technology – consisting of the Simodrive 611D converter system, 1FT6/1FK7 motors on the axes (X1/Z1/X2/Z2 plus loader) as well as a 1PH7 spindle motor – Siemens has made the automation system fit for the future. During this process, the entire wiring was replaced and a new switch cabinet fitted. The Sinumerik 840D’s efficiency made it ideal for integrating and connecting the functionalities of the previously separate controls for the loader and the palleting system with the functionalities of the measuring machine and an outlet system. In order to be able to safely setup in the future when the safety guards are open, the operator chose the internal safety solution, Sinumerik Safety Integrated.
Everyone involved was convinced by the process and results of the retrofit project. The duration of the project was exactly as had been estimated and, right from the beginning, the required quality was achieved without having to change machines or carry out any reworking. After taking only a short time to get used to the machine, operators come to value the simplified processes. Even operators who are new to the machines can get to grips with the new controls much faster than with the previous model. Unlike before, several part programs can now be stored in the controls and managed, loaded and transferred back following any alterations via Motion Control Information System (MCIS) from Siemens by DNC (Direct Numerical Control). This helps keep non-productive time to a minimum in the case of batch sizes from 80 to around 500 parts and, therefore, with frequent production changes.
Maintenance is condition-based and easier to plan
Another focus of the overhaul was optimizing maintenance and service processes. The aim was to move away from the no longer timely, purely reactive approach in the event of a fault, towards a procedure dependant on the actual condition of essential machine components. With ePS Network Services, Siemens provides tailor-made services, sets the IT infrastructure, and implements all required functionalities for efficient condition monitoring on the machine. Generally, these are based on the onboard means of the control system or the machine, therefore, they do not require any additional sensor technology. Relevant operating conditions and process parameters, such as travel distances and speeds, motor currents and torque, are continuously recorded. This data is then used to calculate the actual use and load of the machine or component. The Sinumerik CNC transfers this overwhelming amount of data (in encrypted form in the background) via the Internet to an ePS server, where the information is saved, processed and continuously monitored. This allows arbitrary connection of various parameters and extremely detailed diagnostics, meaning the causes of faults can be pinpointed quickly.
Classic jobs to be carried out periodically (“lubricate”) or “critical” conditions can also be viewed directly on the control system, on the PC in the maintenance office, or by SMS. The machine operator must always confirm the notifications relevant for him; this automates and simplifies the verification process. Authorized users can access the collected data at any time, and, for example, can compare machines or, by means of altered torque sequences, can spot the warning signs for necessary maintenance work at an early stage and plan in advance.
The ultimate aim is to receive a notification at the ideal point in time for a particular machine, for example, sufficiently before the maximum permitted travel distance of an axis is reached. This will enable an inspection or maintenance order to be generated automatically, work to be terminated and spare parts to be ordered well in advance. In order to achieve this, viable empirical values will be collected and the boundaries pushed to their limit.