History
Weighing is defined as finding the weight (mass) of a body. Since weight cannot be measured directly, it was necessary to balance an unknown force against a known force to determine it. The history of this procedure goes back to ancient times. The notion of balance (from the latin bis, meaning twice, and plax, meaning platform came not from one person but from several different peoples or societies. The equal-arm balance, which is found in Egyptian hieroglyphics, was born from the action of the two hands comparing the weight of two objects. The balance first appeared 5000 B.C. and quickly became the main tool for trade.
Then came the first standard weights in bronze or copper, used in Egypt and Asia before the invention of money. Several types of instrument already in use in Ancient Rome are the ancestors of our present-day instruments. The trutina was used for weighing large masses while the moneta was used for small ones. The statera, which is known as the "Roman balance", enabled weights to be measured using just one instrument. In the Middle Ages, the word 'balance' (which means scales) entered the French language. In the late 17th century, Philippe-Auguste replaced the existing unit of weight (the pound) with the marc, a unit of weight that remained in use until 1795 and that was used by most European countries but with different values.
Continual evolution
In the 16th century, weight boxes were developed for small masses. They contained an equal-arm balance mounted on a collapsible column and weights (called monetary weights) and were used to check the mass of gold and silver pieces. In the 17th century, French mathematician and physicist Gilles Personne de Roberval (born in Roberval in the Oise) triggered a revolution in weighing by taking a balance (comprising beam, bearings and knife-edge fulcrum) and adding two platforms above the beam instead of below it.
A century later, Lavoisier perfected the balance and its principles by developing a highly-sensitive (to within a milligram) general-use balance for laboratory use. It was around this time (1795) that archaic systems of weight and measurement were abandoned and replaced by the metric system, driven by the French Revolution.
The 19th century saw a single standard applied throughout the country, as of 1 January 1840. Regulations were even passed on the shape of the weights: cylindrical with a copper grip, hexagonal or rectangular in cast iron with a ring. The Roberval scale was also improved upon by Beranger who reduced side forces and friction by using small secondary beams to replace the force spindles. In England, the weigh bridge was developed with an 'equalizer bar' to enable heavy duty weighing without having to use a large weight scale. Roberval and Beranger scales dominated countertops when, at the dawn of the 20th century, the gauge dial (circular, or an upside-down 'V') balance showing the weight of the object came onto the weighing instruments market. There followed the semi-automatic scales (with one or two platforms), then came automatic scales, before gradually being ousted by 'electronic' scales with strain gauge sensors giving a print-out of the weight and corresponding price…
Sophisticated technologies
Electronics and IT have made present-day weighing instruments fully automated systems, with no input from humans. Several types of weighing-pricing scales in the agrifoods sector that calculate sale price according to a given unit price and a given weight.
'Weight-price without ticket' scales give a price without being able to cumulate several articles or calculate the number and subtotal of transactions made during the day. 'Weight-price with ticket' scales can give a subtotal of several weighing operations as well as a readable print-out of the name of the product (PLU function) and the price to be paid.
'Networked weight-price with ticket' scales go a step further, as they can be linked to several different scales and work with one or more vendors. This is a particularly useful system for traders with wide stalls as it cuts down on all the back-and-forth trips. These instruments can be cable-linked or else wireless, working by radiofrequency or even via a wi-fi network in some cases. Totals and subtotals can be done on any one of the scales.
Some of these devices have software applications performing sales analysis, calculating profit margin, acting as cash register or giving payment breakdowns (cash, cheque or credit card), with some even recording the articles sold loose at unit prices. They can be linked up to a PC (POS terminal), scanner or barcode reader (handheld laser). Some weighing instruments are also able to run stock management operations (managing stock platforms with alerts on stock-outs), perform pre-programmed packaging routines (wrap-weigh-label) while printing out the required text information (traceability, sell-by date, product ingredients… according to all applicable standards) onto a stick-on label.
As the technologies have developed, so have 'automatic product recognition' scales that use special software able to identify the products (fruit, vegetables, etc.) to be weighed. There are also pallet-truck scales (a pallet-truck fitted with scales), crane-type scales with a hook (for weighing meat carcasses offloaded from refrigerated lorries), wall-mounted scales (for butchers), heavy-duty weigh-bridges (from 0.5 to 100 tonnes), etc. …
Highly accuracy capabilities...
Weighing instruments now deploy high-tech systems and materials for ultra-precision weighing.
Thus, load receptors can be split into three main groups:
- mechanical load receptors where the weight is transmitted and spread by the lever arm: this kind of instrument has fallen from favour as it requires high-pressure-resistant materials and qualified technicians to adjust the system, but remains in use in areas where there is no immediate power supply;
- electronic load receptors (with strain gauge sensors) based on one or more metal beams fitted with strain sensors to measure resistance of the beam to deflection under the weight of an object. There are both multi-sensor systems (for clean, dry environments with temperatures ranging from +10°C to +40°C) and single-sensor system with a single metal bar (temperatures from -10°C to +40°C);
- the magnetic pan (on scales for laboratory preparations, e.g. 52 g/0.00001 g) which balances a metal beam carrying the load to be weighed by sending an electric current through a magnetic coil. The level of electrical current is then converted into an indication of the weight.
In addition, present-day weighing instruments are built to meet protection indexes using materials able to resist all kinds of environmental stresses (water, temperature swings, dust, impacts, etc.) and stand up to intensive cleaning (karcher high-pressure cleaning, detergent agents), etc.
Legislation and the market
All weighing instruments used in situations governed by regulations (e.g. sales to the public) have to meet strict regulatory requirements and are submitted to regular testing. It is compulsory to have these testing procedures validated by a State-approved testing body (such as the DRIRE – Regional Department for Industry, Research and the Environment) qualified to commit the liability of the user.
System verification is done via two types of test:
- administrative conformity (the scales have to be accompanied by a metrology logbook showing all checks performed), be sealed to prevent the user for tampering with the settings, and be a State-approved model and be labelled with readable, understandable instructions to the buyer, etc.,
- metrology tests (check of zero-load balance, off-centre testing at several points on the platform, matching to standard weights, light-load adjustment capacity, etc.).
If the instrument is found non-conform (a red sticker is stuck on), it has to be repaired, or even withdrawn from sale (scrapped) in the worst-case scenario. If the instrument is conform it gets a green sticker that means it has two-year validity as scales (below 30 kg) used in sales direct to the public, and 12-month validity for other users. The testing authority will not undertake any work on the scales. This is the role of the LNE (National Testing Laboratory)-certified repairs agency. The weighing instruments market boomed during changeover to the euro (1st of January, 2001) then dropped off between 2002 and 2005, although 2006 has seen it fight back. The market is nevertheless stable, with relatively few peaks or troughs. An average 35,000 weight-price scales are sold in the agrifoods sector every year, and 5,000 units per year for weighing-stations…
(source : DRIRE, La Corpo, Mettler-Toledo, La Bovida, Jac’Pesage, Pesage 94)
Duriez Francis
Pro reviews
Bernard Soulié
(directeur marketing - division commerce de Mettler Toledo France)
« Notre règle est d’apporter la meilleure solution globale… Leader mondial du secteur pesage-étiquetage, nous sommes le seul fabricant, par exemple, à pouvoir équiper en totalité un atelier de découpe, en système automatisé. Le pesage est passé d’un mode mécanique et manuel, à l’ère de l’électronique et de la connectique… Après les alertes sanitaires (type ESB et autres…), l’obligation de traçabilité a généré des besoins d’identification comme la connexion informatique et la mise en place de normes spécifiques : IFS (International Food Standard) pour l’UE et le BRC (British Retail Consortium) pour la Grande-Bretagne.
Nous allons commercialiser des instruments de type IP 69K (degré de protection à l’eau et à la poussière) sous HACCP, et un nouveau groupe de pesage-étiquetage (base PC, grand écran tactile, réseau wi-fi, totalement connectable).
La révolution est dans la gestion totale de la traçabilité du produit et parmi les voies d’avenir, il y a la reconnaissance automatique du produit, l’intégration des cartes PC dans les indicateurs de poids… L’évolution du pesage tend vers un meilleur service global.
Eddy Zimero
(p-dg de la société Jac’Pesage - Marché de Rungis)
« Notre entreprise dont l’existence et l’expérience remontent à plus de soixante ans est diversifiée dans le secteur du pesage. Nous sommes distributeur, réparateur certifié par le LNE (Laboratoire National d’Essais) et vérificateur agréé par la DRIRE (Direction Régionale de l’Industrie, de la Recherche, de l’Environnement). Nous sommes donc audités et contrôlés par la DRIRE plusieurs fois/an. Les matériels les plus vendus sont les balances en réseau de type filaire. Elles permettent de gagner un temps important sur les linéaires à plusieurs vendeurs. Les appareils en radio fréquence sont encore trop peu employés. Pour être utilisables à la vente, les instruments de pesage doivent être obligatoirement conformes à la loi...
Aujourd’hui, l’évolution réside dans des balances connectées à un logiciel informatique réalisant plusieurs fonctions : analyse de vente, calcul de marge, gestion de stock, caisse enregistreuse, étiquetage et traçabilité... Désormais, la technologie est omniprésente dans le pesage...».
Alain Valenza
(directeur régional IdF de la société La Bovida - Marché de Rungis)
« Figurant dans les trois premières entreprises d’accessoires en France, nous sommes distributeur de matériels de pesage et nous sous-traitons le contrôle à un bureau de vérification agréé. Nous commercialisons surtout des balances de comptoir (15 kg) pour nos clients des métiers de bouche, des balances 60 kg et des balances murales pour bouchers et charcutiers. Les plus vendues sont les balances électroniques. Le pesage a beaucoup évolué, notamment par la mise en place de cahiers des charges très précis où l’informatique et l’électronique jouent un rôle majeur. De plus, ces instruments sont devenus très résistants et répondent à des indices de protection élevés. Ils restent précis et fiables après un lavage au Karcher, à la poussière, aux basses et hautes températures et à certaines pressions. Le passage à l’euro a permis de renouveler une grande partie du parc et tous les distributeurs ont fait d’excellentes ventes. Aujourd’hui, le marché est revenu à un niveau de plus faible amplitude. Pour notre magasin de Rungis, le pesage représente 5% du CA...».
Silvio Piccini
(dirigeant de la société Pesage 94 - Marché de Rungis)
« D’abord employé d’un fabricant d’une grande marque qui a du cesser ses activités, je me suis mis à mon compte en février 1985, toujours sur le Marché de Rungis. Je suis titulaire de plusieurs agréments : réparation, étalonnage, vérification, Iso 9001 version 2000. De fait, je suis soumis aux contrôles de la DRIRE. Les instruments les plus demandés vont du pont-bascule 1500 kg à la balance 60 kg par 20g, en passant par les balances pour laboratoires, au pont de 100t. Autrefois mécaniques (dites IPFNA : instrument de pesage à fonctionnement non automatique), les machines sont, aujourd’hui, totalement électroniques (dites IPFA : instrument de pesage à fonctionnement automatique) et beaucoup plus fiables. Certaines sont non filaires et fonctionnent en wi-fi, évitant les pannes de courant. A l’évidence, la durée de vie d’un appareil de pesage dépend de son entretien. Incontournables des opérations de commerce, les instruments de pesage restent un marché assez stable... ».
Jean-Paul Robinet
(responsable technique de la société La Corpo - Marché de Rungis)
«L’activité pesage est très importante dans notre entreprise et l’essentiel de nos ventes concerne les balances poids/prix de 15kg pour le commerce de détail. Celles-ci cumulent plusieurs opérations, plusieurs produits et la ventilation se fait par touches « famille » et PLU (par pré-programmation, chaque touche correspondant à un produit et à un prix). Il s’agit des balances de contrôle pour la vente directe au public selon les applications en métrologie légale, mais aussi des balances hors métrologie légale non destinées à la vente, ou encore celles destinées au contrôle des marchandises et aux préparations en laboratoire pour les métiers de bouche... Aujourd’hui, tous ces instruments sont électroniques et leurs prix ont baissé par rapport à ceux d’il y a dix ans...».
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