In recent years, China’s oil processing industry has developed rapidly, but it is limited by market and technology, and the development of edible oil packaging machinery is relatively slow. Before 2006, middle and high-end edible oil packaging equipment was mainly imported from abroad, which was basically monopolized by companies such as Weightpack, Sidel and Krones, etc., and only low-end packaging machinery with volumetric or liquid-level type could be produced in China, which was far behind the advanced foreign products in technology. Subsequently, due to the importance attached by the state to the safety of edible oil and the need for a development strategy, edible oil packaging machinery showed a high-speed development trend. Some domestic packaging machinery enterprises with strong processing and manufacturing capabilities have made the whole domestic production technology develop by leaps and bounds by introducing technology, digesting and absorbing it. Especially in recent years, domestic filling equipment has increased rapidly in the domestic market share. It is roughly estimated that among the relatively high-speed filling equipment newly purchased by domestic oil and fat enterprises, the proportion of domestic equipment has reached about 70%, and the imported equipment selected is mainly bottle box testing equipment and a few high-speed labeling machines or bottle-blowing machines. According to the situation of small packaging production lines purchased by several major domestic small packaging brand manufacturers in recent years, except bottle and box testing equipment and individual filling machines, almost all of them are domestic filling equipment. In terms of filling accuracy, domestic weighing and filling equipment have reached below ±2.0g (based on 5L products), and the qualified rate of capping has reached above 99.9%, which has basically reached or approached the technical level of imported equipment, which indicates that the design and manufacturing capacity of domestic edible oil packaging machinery has made considerable progress.
Development of filling machinery
1. Filling speed
High speed, energy saving and automation are the inevitable trends in the filling machinery industry. From the perspective of market sales, consumers are more inclined to small package products with small capacity and quick turnover, and the production capacity of the production line is gradually developing from low speed to high speed. The technology of high-precision weighing and filling production line with 6 000 bottles /h is relatively mature. Judging from the development prospect of edible oil demand in China and the manufacturing technology of packaging machinery, high-precision filling machine products with filling speed above 6 000 bottles /h and bottle blowing and filling machines are the future development directions.
2. Diversity of filling specifications
China’s edible oil industry has experienced decades of development, and the product types and packaging forms have been greatly enriched. Consumers’ requirements for packaging are also getting higher and higher, which requires edible oil processing enterprises to be innovative and changeable in packaging forms, and refined and beautiful in packaging quality. Due to the different product terminals, the requirements for filling specifications are also different, and the forms of packaged products are developing in a diversified direction. The commonly used 5L bottle specifications can no longer meet the market competition needs, and some oil and fat enterprises even have more than 10 product specifications. Under this market background, an edible oil filling production line must meet the requirements of various packaging specifications at the same time. Sometimes, it is necessary to switch the bottle types of different specifications (such as 1.8, 2.5, 4 and 5L, etc.), and sometimes it is desirable to switch between glass bottles and PET bottles. This requires the filling equipment to have strong adaptability, which can adapt to more kinds of filling materials, more specifications of filling containers and even different filling processes. As an equipment manufacturer, it must also meet the needs of the market. When replacing different bottle and box types, the accessories of related packaging equipment should be replaced in the shortest time, and the non-production time should be reduced as much as possible. This technology is called “quick replacement”. At present, a high-end filling machine in China can fill different varieties (such as 5L, 4L, etc.) as well as glass bottles and PET bottles within a certain range. The switching of different varieties can be completed in a few minutes, which is quick and convenient.
3. Intelligent technology of packaging machinery
The high efficiency of the edible oil packaging production process is mainly realized by mechatronics technology and automatic control technology. Continuous automatic production equipment replaces intermittent semi-automatic production equipment so that the production line can realize continuous production, specialized operation, automatic adjustment and large-scale operation, which can significantly improve production efficiency and economic benefits. With the scale and centralization of the edible oil industry, high-speed and high-efficiency production equipment is needed, which puts forward higher requirements for the speed and performance of edible oil-filling machinery. At present, new intelligent equipment such as highly intelligent numerical control systems, encoders, digital control components and dynamic load control has been widely used in packaging machinery and equipment, which has the characteristics of independence, flexibility, correct operation, high efficiency and compatibility in the operation process. The mechatronics automation technology of edible oil packaging machinery has promoted the improvement of the overall level of domestic packaging equipment and large-scale production.
Application configuration of filling machinery
1. Filling machine
In the packaging production of edible oil, the filling is a very important link, and the quality of products is directly affected by the quality of filling technology and equipment. Because the physical and chemical properties of liquid materials are different, there are different requirements for filling. The packaging materials and containers are diverse, so when choosing a filling machine, besides the characteristics of the materials themselves, the packaging containers, filling precision, material value, packaging cost and production efficiency must also be comprehensively considered. Compared with the original semi-automatic form, the automatic edible oil filling machine realizes the integration of mechanical and electrical control for filling, which greatly reduces labor costs and is superior to the original semi-automatic machine in accuracy. The use of an automatic edible oil filling machine has greatly improved the working efficiency of the packaging line and reduced the cost of products. At present, there are two types of filling machines used in edible oil: rotary type and linear type. For domestic rotary filling machines, the capacity of 5L bottles can reach 6 000 bottles /h, and that of the linear filling machines with 5L bottles in double rows can reach 3 000 bottles/h. For mainstream varieties that don’t need to change the bottle shape frequently, it is more appropriate to choose a rotary machine, while for filling products with small output and many varieties, a linear machine is more appropriate, which is beneficial to the change of bottle shape.
There are many filling methods and metering forms. At present, electronic weighing type, liquid level control type, volumetric type and induction flowmeter type are mainly used for edible oil. They all have their own characteristics and application scope. See Table 1 and Table 2. With the increasing demand for the precision of edible oil filling products, weighing filling machine is more and more applied to the filling of edible oil, which is a more accurate filling method that uses electronic weighing to control the filling quantity. Each electronic scale can independently set the value to be filled to ensure the adjustment of filling accuracy. The filling method is divided into two parts: pre-filling and fine-filling, and the electronic scale randomly detects the filling quality. When the filling quality reaches the set value, the electronic scale sends a signal to close all filling valves and stop filling. In the nozzle of the filling valve, the filling valve has a special lower valve cavity by adopting a special anti-dripping design. Through the special decompression of the valve cavity, a liquid film is formed, which has the functions of anti-foaming and anti-dripping.
The biggest advantage of weighing canning machines is cost saving. Based on 5L bottled oil, the average accuracy of domestic weighing canning machines can reach 2.0g (σ value), while the accuracy of a general canning machine is between 10-20 g. After comparison, an average 5L bottle of oil can save 10g of oil. According to the daily production scale of 40,000 bottles, it is estimated that about 400kg of oil can be saved every day, and 10.4t of the edible oil can be saved every month, which will produce very significant economic benefits.
PET bottle is the most important packaging container for edible oil. Because of its advantages of a lightweight, good transparency, beautiful appearance and convenient transportation, it is gradually replacing glass containers and other packaging containers. In order to minimize the possible pollution in the filling process and the logistics links of packaging materials, more and more edible oils are filled by bottle-making and filling. Bottle-making machines are usually used in factories with a daily output of more than 20,000 boxes. Its most prominent advantage is that it reduces the transportation and storage of packages, which can avoid pollution to the maximum extent and reduce the intermediate cost.
There are two ways to make bottles: the one-step method and the two-step method. In the one-step method, the molding, cooling, heating, stretching, inflation and bottle taking-out of the parison are all completed on one machine in turn; The two-step rule is that the molding of parison and bottle blowing is carried out on two machines, namely, the first step is to mold the parison by injection molding, and the second step is to blow the bottle. At present, edible oil bottle-making is mostly a two-step bottle-making process.
In terms of production efficiency, product accuracy and energy consumption, bottle-blowing machines in China have always followed the advanced bottle-blowing machine technologies in Europe and America, such as high-speed bottle blowing machines produced in Italy, France and Japan. After nearly 10 years of development, domestic bottle-blowing machine production has gradually formed a scale effect. Focusing on the two major themes of energy saving and product innovation, we have made solid efforts to advance, and have successfully developed fully automatic bottle blowing machines for PET bottles of 5, 10 and 20L specifications, with a maximum capacity of 5L bottles reaching 8 000 bottles/h. Adopting the concept of full-automatic design, technical innovation has been made in servo-controlled heating system, PID closed-loop heating control system, fast energy-saving blowing molding system and bottle blank precise temperature control system, and its technical manufacturing has approached or reached the international advanced level. At the same time, the air recovery system of bottle-blowing machines has been developed, which can recover 30% ~ 50% of the air for reuse, thus greatly saving energy consumption. The produced PET bottle has a uniform wall thickness, high transparency and good product consistency. The conveying line system of the automatic bottle-blowing machine adopts the most advanced technology and the highest quality materials, which fully meets the requirements of fluency, flexibility and high efficiency. The modular structure is beneficial to transport different plastic bottles and products, and reduces the time for changing packaging specifications. This will break the technical monopoly of foreign multinational companies and effectively promote the development of China’s packaging machinery and equipment manufacturing industry towards high quality, high efficiency and high energy saving.
Automatic labeling machines
There are many kinds of automatic labeling machines, which are suitable for all walks of life. With the fierce competition in the market, all products need labels to highlight their own brands, and the labels should also show the characteristics of the products, such as ingredient description, capacity description and manufacturer’s information, etc., so the products must be labeled. Overall, the labeling accuracy and speed of German products are the first in the world, followed by Italian labeling machines. Although the accuracy and speed are not comparable to those of Germany, the advantage lies in its wide applicability. Domestic machinery manufacturers began to imitate German and Italian labeling machines in the mid-1990s, from manufacturing spare parts, to renovating and then making the whole machine, and gradually formed a scale. Since around 2003, it has developed rapidly, and the production speed is below 40 000 bottles /h (mainly in the beer and beverage industry). Before 2007, some large oil processing enterprises used imported labeling machines, while small factories used manual labeling or domestic labeling machines because of low and unstable output. In the edible oil industry, cold glue labeling machines and self-adhesive labeling machines are widely used at present. Self-adhesive labelers are mainly linear labelers, and the speed of applying 5L varieties is below 1 500 bottles/h. Self-adhesive labels are suitable for hard bottles such as glass bottles, and the labels are flat and not easy to wrinkle. Olive oil (glass bottles) are usually labeled with a self-adhesive label machine, with one label on the front and one label on the back. Straight-line double-sided self-adhesive label machine can be used for square bottles. If it’s a PET bottle, the label can’t be pasted flat because of the concave ribs on the surface, so it’s easy to wrinkle. The cold labeling machines are basically rotary labeling machines, with good labeling quality, fewer wrinkles on the label surface, and low label cost. The speed of labeling 5L varieties is between 2 000 and 8 000 bottles/h. In recent years, the output of medium packaging oil (10 ~ 20L) has increased rapidly, so there is a demand for automatic labeling machines for medium packaging, and the speed is generally between 400 ~ 1 600 bottles/h. Cold glue labeling machine is the mainstream choice of the oil and fat industry at present. At present, some large oil and fat processing enterprises in China basically adopt cold glue labeling machines, mainly because of the following considerations: the speed is fast, and the production line with more than 3 000 bottles /h can only be rotary labeling machine; The cost of auxiliary materials is low and the output is large, so the material cost is strictly controlled, and the cost of coated paper labels is low; Good appearance, big brands have higher requirements for product appearance quality, and coated paper label is the best choice compared with PET soft bottle.
There is another kind of labeling machine, which is quite different from the principle of labeling machine, but it is also used in the oil industry and is suitable for bottles with irregular shapes. The principle is that the pre-cut annular sleeve PVC label is sleeved on the outer wall of the bottle, and then the PVC label is contracted through the heating channel, so as to be fastened on the bottle. At present, Arowana sesame oil (conical bottle) and Helium sunflower oil (elliptical bottle) all use labeling machines, and the production line speed is 3 000-5 000 bottles/h.
Edible oil is an essential consumer product for people’s lives, and it is an important food that provides human body heat energy and essential fatty acids and promotes the absorption of fat-soluble vitamins. In order to further ensure the safety of edible oil consumption, bulk edible oil will be withdrawn from the consumer market one after another. The quality of edible oil filling machinery directly affects our living standards, and also relates to the production efficiency and profit of oil enterprises. At present, an all-in-one bottle-blowing and filling machine imported by a domestic oil processing enterprise, which represents the highest level of small packaging technology in the world today, has an accuracy of 1g. Besides avoiding bottle pollution to the maximum extent, it also has the ability to quickly change products. The bottle-blowing mold can be completely replaced in 20min and converted into other specifications. From this point of view, the filling machine with environmental protection, energy saving, high efficiency, high precision, intelligent control, diversified functions and integrated technology will be the inevitable trend of the development of the edible oil filling industry in China.