Process engineering

cfi/Ber. DKG 93 (2016) No. 3 E 1

Today, fully automatic robot-assisted cup sticking plants are in use, which are capa-ble of assembling and fettling pressure-cast handles with pressed or still rolled mugs and soup bowls. Depending on the development level of the porcelain factory, old and new methods are applied in parallel as the integrated auto-mation capability of the cup production is strongly infl uenced by the design of cup and handle. DORST TECHNOLOGIES now presents a new and worldwide unique process for the production of mugs and cups, including handle, by isostatic pressing.

Fundamentals – production of fl atware

Decades of experience in isostatic dry press-ing of fl atware formed the basis for this in-novation from DORST TECHNOLOGIES. The company managed to re-interpret and ad-vance this known forming technology and

eventually transfer it onto monolithic press-ing of cups including handle. Spray-dried granulate is fi lled between two tool halves with specially shaped plastic di-aphragms. A hydraulic press closes the two tool halves. After that, the granulate under-goes compaction by hydraulic pressure act-ing through the diaphragms.

Introduction

Since the beginning of industrialization in the porcelain industry, nothing has changed so far with regard to the multi-stage pro-duction method, aside from a few isolated approaches by means of monolithic pres-sure casting, even if the production pro-cessing and methods as well as the degree of automation of the individual steps have been modernized. It is still state-of-the-art to turn the cup from plastic mass, to stick the plaster-cast handle manually and to fet-tle the cup right with it. In the meantime, concepts have been de-veloped for dry pressing of the mug from granulate and to provide it with handles that are now as before cast. Solutions were invented to automate the sticking opera-tion, e.g. sticking by vibration taking advan-tage of the slip thixotropy of the handle. In-stead of plaster-cast handle manufacturing, the pressure casting process has made its arrival in the production of handles.

Isostatic Press of Cup Bodies with Handle – ISOCUPManufacturing of Cups, Mugs and Soup Bowls from Fine Ceramics

in a Single Operating Cycle

H.-Ch. Schmidt, F. Köppl

The fabrication of mugs, cups and soup bowls has always been characterized by the separate production of the base body and the handle; which are assembled in an additional production step by sticking before they constitute a com-plete article. DORST TECHNOLOGIES now presents a new and worldwide unique process for the produc-tion of mugs and cups, including handle, by isostatic pressing.

Fig. 1 Cups with handles, isostatically pressed in a single operating cycle

Hans-Christian Schmidt,

Florian Köppl

DORST TECHNOLOGIES

82431 Kochel am See, Germany

Corresponding author: F. Köppl

E-mail: Florian.Koeppl@dorst.de

www.dorst.de

Keywords: isostatic cup press,

monolithic pressed cup with handle,

new design variety

E 2 cfi/Ber. DKG 93 (2016) No. 3

Process engineering

The above described plant is cable of shap-ing articles with different outer and inner contour. Cups can be externally and inter-nally angular. Inclined and asymmetrical geometries are possible.In particular, the process ensures the pro-duction of outer and inner contours with undercut or of bellied cup shapes. The high precision of isostatic pressing ena-bles the affixing of any brands, embossing or reliefs both on the outside and on the inside.

The advantages at a glance

In high analogy to isostatic pressing of flat-ware it is now finally possible to reliably produce cups with handle from dry granu-late in a single operation cycle. The advantages in the production of flat-ware and mugs/cups are as follows:• Same production granulate• Same material logistics• Identical forming process (isostatic press-

ing)• Similar tool structure and process control• Same firing process• Parallel production progress (cycle time to

availability of final product)• Known adjustment, operation and main-

tenance of the machinery• High flexibility and short set-up times• Very high reproducibility• Low space and energy requirements for

machinery and equipment.

Perspectives

The systemic change from rolled flatware to isostatically pressed flatware had been developed and initiated by DORST decades ago. Nevertheless, one generation has been needed to adopt the isostatic process na-tionwide as the accepted economically ef-ficient standard method for the production of flatware in the factories all around the world. It is to be expected that the dry pressing of cups with handle will replace the traditional shaping much faster and will become the new standard method.The changes in the tableware market and today’s buying behavior of the consum-ers might have an accelerating impact. The classic porcelain manufacturer with a broad product range is increasingly outri-valed by specialist manufacturers of cheap mass-produced goods. The consumer buys

Thanks to the precise manipulation of the articles by the robots, even thin-walled and sensitive cups and handles can be produced without problems. Depending on cup, handle shape or optical demand, different devices such as mills and sponges are available for finishing the cup rim and for fettling possible pressing seams. Here special emphasis was placed on quick and easy change of profile sponges in case of wear or mould change. As a result, the plant PHT200 with RPT1 pro-vides finished and sturdy cups with handle, reading for glazing or firing. Intermediate drying is not necessary. The reproducibility is so high that a necessary quality control, as this is always cited as an argument for manual sticking, is limited to a few sample tests analogous to flatware pressing. Altogether, the plant is designed for a maxi-mum output of up to 360 articles per hour. The real output depends on the pressing cycle and the article geometry.

Innovative design variety and a new design vocabulary

The isostatic pressing of mugs and cups with handle allows formulating a new de-sign vocabulary for system- and dinnerware.

Technology in terms of machine and tooling

High economic efficiency and competitive-ness as compared with established produc-tion methods in mind, a completely new plant, consisting of press, fettling device and tooling system, was developed for the production of cups. The new horizontal press PHT200 is de-signed as dual head system, with hydrau-lic locking cylinders in linear arrangement, each operating independently. Both press-ing heads are equipped with an identical tool for the same article. The specific tooling system is designed in such a manner that whole product families can be reproduced with minimum set-up expenditure and at minimum cost. For ex-ample, if the cup body is identical and only the handle geometry differs, there will be no need to change the entire tool. The re-placement of flexible mould parts will be sufficient and can be done within a few minutes. Noteworthy is the low scrap rate on the flash at the cup rim. Alternately, a robot removes an article ei-ther from the left or the right pressing head for further treatment by subsequent fettling robots.

Fig. 2 Isostatic dual head press PHT200 with fettling robot RPT1

Process engineering

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with increased reproducibility. All told, the new process from DORST TECHNOLOGIES provides an innovative option for the eco-nomic production of cups including handles. As of now and the year round, a team of engineers, process and tool specialists and a test machine are available for consult-ing, test-runs and project planning at the DORST-own Technology Center in Kochel am See.

and received highest recognition by experts from around the world. The new forming process has a high analogy to isostatic flat-ware pressing and, as compared with exist-ing processes, opens up high saving poten-tials with regard to the preparation and the provision of material, its forming and the necessary production and storage areas. In addition, potential sources of error in the production process are eliminated, coupled

less complete dinner services, but seeks, if necessary, for individual pieces and shape combinations. Expediency, trendy appear-ance and price go before time-lessness and intrinsic value, similar to developments already observed in other consumer indus-tries. To this end the perspectives can be consid-ered as very favorable to produce innovative and unusual cup bodies using the new pro-cess. New freedom in designing will open up for modelers and design engineers. A limitation should be mentioned, namely that isostatic pressing of cups with handle will – from an aesthetical point of view – not always produce results that are compat-ible with existing classical whiteware. This means, where whiteware is subject to a long-term replacement obligation and identical appearance is always required, the classic methods still have their entitlement.This will change only by and by, when more and more whiteware will principally be based on the new production process.

Summary

The initial presentation of isostatic pressing of cups with handles on the occasion of the Munich fair ceramitec 2015, DORST TECH-NOLOGIES has caused a stir in the industry

Fig. 3 One-piece isostatically pressed cup with bellied shape on asymmetrical saucer (flash-free tool)