Comparison Between Internal&External Stirrers

8/9/2019 Comparison Between Internal&External Stirrers

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CVS MAK NAAAT SAN. ve TC.LTD.

theMill for Minimi lls

Dilovas Organize Sanayi Blgesi 3. Km Muallimky Cad. No:21Gebze 41400 Kocaeli / TRKYE

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Tel. +90 262 759 1505 Fax. +90 262 759 1880 [email protected] www.cvs.com.tr

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CVS MAKINA

COMPARISON

BETWEEN

INTERNAL AND EXTERNAL

STIRRERS
mailto:[email protected]://www.cvs.com.tr/http://www.cvs.com.tr/mailto:[email protected]


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1. Introduction ................................................................................................................................3

2. Description..................................................................................................................................3

2.1 Internal type MEMS (without stainless steel case) ...............................................................5

2.2 External type MEMS (with stainless steel case) ....................................................................7

3. Comparison table ........................................................................................................................8


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1. Introduction

This document compares internal and external type M-EMS, from a structural and construction

standpoint, just as from mould engineering, operating practice and performance.

2. Description

From a structural & construction standpoint, M-EMS can be designed in two typical

configurations: Internal (also referred to as "open frame") and External ("closed frame").

Figure 1: Internal and external MEMS

Typical Internal MEMS, with bolt-on lifting device(red) Typical External MEMS

Internal MEMS drawing External MEMS drawing

Bolt-on liftin deviceWater OUT

Water IN

Water IN

Water OUT

Protection case contains the

ma netic core and the coils


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As it may be immediately noticed, Internal MEMS do not have an external stainless steel

protection case, while External MEMS do have it.

Consequently, the weight, the amount of material required (stainless steel), the manufacturingwork and the price are higher for the External type (at same power rating).

Let now see their differences from the mould engineering and operating practice standpoints.


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2.1 INTERNAL TYPE MEMS (WITHOUT STAINLESS STEEL CASE)

They are installed inside the mould or mould support assembly, in a water sub-chamber. This

sub-chamber is necessary to separate the primary mould water circuit from the MEMS watercircuit. Water flows, in a controlled way, inside this sub-chamber thus cooling the stirrer's

internal coils. So, the sub-chamber has a water inlet and a water outlet.

Figure 2: Internal MEMS

When cartridge-type moulds are planned, this means that the cartridge support (Mould Support

Assembly) must create a sealed sub-chamber. This imposes a relatively more complex mould

engineering and the use of O-rings to separate MEMS water-inlet from water-outlet zones and

between sub-chamber and top cover (see fig. 3).


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Figure 3: Internal MEMS Mould installation

From the manipulation and installation point-of-view, Internal MEMS require a little more careful

handling due to the exposed magnetic core and cables (see fig. 1)

cartridge-type

sub-chamber

Internal M-EMS

Mould Support

Assembl

MEMS Water OUT

MEMS Water IN


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2.2 EXTERNAL TYPE MEMS (WITH STAINLESS STEEL CASE)

They are installed outside the mould,

and do not require a water sub-

chamber, having their own

independent case.

The water cooling circuit is completely

self-contained in the MEMS and

independent; there are only one

water-inlet pipe and one water-outlet

pipe, both with quick-coupling

connectors.

There is no imposition for the mould engineering because they live separately. The MEMS is

simply placed inside the std. Mould Support Assembly, around the cartridge mould (see fig. 4),

and no sub-chamber and O-rings

must be foreseen. In this way the

mould engineering is simplified.

From the manipulation and

installation point-of-view, External

MEMS are intrinsically self-

protected by the stainless steel

case so they don't need careful

handling.

The magnetic core and the cooling

circuit are not exposed.

3.

MEMS

Mould

Water Water

Connection Box

cartridge-type

mould

sub-chamber

External M-EMS

Mould

Support

Assembly

Figure 4: External type MEMS mould installation


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Comparison table

Internal MEMS External MEMS

Operating practice and

safetyCareful Higher

Mould Engineering Relatively more complex Simplified

Cost of Moulds Some higher Lower

Cost of MEMS Lower Higher

Cooling circuitTo be created in the mould

engineering

Self-contained and

independent

Inverter supply Lower power, cheaperHigher power, some higher

cost

It must be noted that internal MEMS must be as many as the moulds because each mould musthave its own stirrer assembled inside.

In the following table it is possible to compare the energy consumption levels between internal

MEMS and external MEMS. The values indicated in the table refer to MEMS installed on standard

moulds of the main manufactures.

Active Pow er

[kW]

20 40 40 60 60 90 90 120

Castingsectionsize

[mm]

80 120 I E

100 140 I E

120 160 I E

140 200 I E


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Note:

I: internal MEMS

E: external MEMS

Increasing the radius of the stirrer, it is necessary to increase the active power according to a

no-linear rule to guarantee the same electric magnetic field and the same metallurgical effects

on billet. The external MEMS has a wider radius than internal MEMS and therefore it is

necessary to increase its active power.

Documents

Comparison Between Internal&External Stirrers