Vending machining light Profile project

Writer: Carlos; Role: Design director

In 2022,GREFEE responded to customers requirements and designed a freezer lamp profile suitable for the European market. We have made new breakthroughs this time in scattered light, concentrated light,and other applications. This is a lamp tube used in the vending machine which is made of food-grade materials and uses extrusion technology. It is cost-effective and of guaranteed quality.

Processes used: extrusion mold, injection mold, stamping.

Surface treatment: galvanizing.

Materials used: PC, stainless steel 304.

Application of extruded products:

Extrusion molding is a molding processing method with many variations, high productivity, strong adaptability, wide range of uses, and used most widely in the field of plastic material processing.

Extrusion molds only require relatively simple equipment, making operation relatively straightforward. There is also not too strict requirements in terms of location and environmental conditions for production. Hence,extrusion is widely used in multiple fields. For example, sunroofs and seat rails in cars; Items in daily life such as light tubes, door and window profiles, wires and cables, PVC water pipes; Medical equipment rails, conveyor belts, and so on.

Design considerations for extruded products:

1.The design of extrusion products is the same as that of injection molding, die casting and other, the most important thing is that the wall thickness of the product should be uniform. If the wall thickness difference is too large, it will cause uneven flow rate during the production process, and also make the cooling of the product uneven, resulting in deformation, dimensional deviation and other problems

2. Avoid hollow areas within a product structure. Because the plastic extrusion is a continuous process, the products strength is low when it is just extruded, it needs to be supported by external air pressure, mandrels, etc. to maintain the shape and avoid deformation. If there is a hollow area inside the product, a vacuum environment is formed, and the internal high pressure will cause the product to dent. Therefore, when designing complex product structures, cutting is a common method used to avoid hollowing.

Design of lamp tube

Design a light tube that is different from most ones in the market is a challenge. Factors like aesthetics, practicality, size, assembly, and transparency requirements are all we need to consider. Combining all of these factors together to achieve a balance is the key to the success of the product. The product consists of four parts. The main body is a lamp tube, with side covers on both sides of the lamp tube, fixing clips at the bottom of the lamp tube, and LED light strips inside the lamp tube.

Most of the similar products on the market have a split structure, with aluminum as the fixing material of the bottom light strip and PC translucent as the top cover. The split design makes it more convenient in structure and also easier to produce. In the meantime, hidden risk comes as it may cause the top cover to fall off and the LED light strip breaks when accidentally touched.

To have more variability in the installation of the light tube, we have the removable side covers on both sides of the light tube. There is a“U”groove on the side cover for the convenience of installation. When the length is lower than 1.5 meters, it can still be installed by the two side covers. When the length exceeds 1.5 meters, we need to install a fixing clip in the middle of the lamp tube to keep it in a straight line.

The length of the light tube depends on the size of the refrigerator,and we also have a range of 1.2 to 2.5 meters to choose from. When the length of the lamp tube exceeds 1.5 meters and the lamp tube is on the side of the freezer, the installation will fail because it will cause the middle position of the lamp tube to bend due to heavy force. Thus, we have two fixed buckles at the bottom of the lamp tube to facilitate product installation and ensure the service life of the lamp tube.

Another reason is due to the usage environment. When the bottom of the lamp tube is in contact with the freezer as a whole, there is a risk of bonding with the freezer in special circumstances. To avoid such situations, we have designed a 3mm bottom drag at the bottom of the bottom clamp to prevent direct contact between the lamp tube and the freezer.

Moreover, for the material, we chose acrylic for the lighting fixtures in most cases due to its good light transmission and brittle material. Based on the usage environment of the freezer, the product will always be in a low-temperature environment. The internal LED will generate heat when working, which may cause a risk of bursting the lamp tube.

Therefore, we choose PC material, which is more resilient and has characteristics that are more suitable for the product design. The arc shape in the front of the product also avoids the risk of cracking during production. We use 304 steel material with a thickness of 0.4mm for the fixed buckle which is made by stamping with a metal continuous mold process. After galvanizing, the surface hardness of the material is increased.

The selection of LED lighting and tube material: We have the options with LED light strips with three color temperatures of 3000K, 4000K, and 6500K, as well as two types of tube materials for customers to choose from: bright or matte. The light transmittance of the tube is maintained at 85% -90%.

Based on the weather in Western European, which is often cloudy and rainy. A 3000K LED strip will appear dim in matte tubes, while a 6000K strip will be more dazzling. Therefore, we recommend a milder lighting to customers in terms of color temperature and use a 4000K LED strip. The lamp tube is made of more textured matte PC material and paired with a 4000K light strip.

Assembly and detail design

Installation of light strip: the light strip is 6mm width and 1mm thick. As the general length of light strip is 50cm, and we can extend it via welding to achieve the targeted length. We consider that possibility of errors during the light strip welding process, thus, in case the lighting quality is affected with light strip sways inside the lamp tube, the size of groove we designed is 6.3mm X 1.2mm.It was tested that the size can fit into the long light tube, and at the same time, it fixed the light strip swaying problems.

Fixed buckle installation. The buckle is connected to the freezer through screws and fixed in place. To install the light tube, start with inserting one side of the light tube into the fixed buckle, and then press the other side into the buckle. We have used a large angle design at the entrance of the buckle, and the material of the buckle is the 304 steel. Moreover, the buckle has been galvanized, and the surface smoothness has reached Ra3.2, so the installation of the lamp tube would be convenient.

As the lamp tube uses extrusion technology and the length of the lamp tube is cut by machine , the two ends of the lamp tube are straight, which requires the inner part of the side cover to maintain an absolute angular contact with the lamp tube. We have designed a sinking of 0.2mm at the contact position between the side cover and the lamp tube to avoid interference during installation.

GREFEE has stuck to high quality material selection principles. We used SKD11 at the key locations with high welding resistance and high toughness. The injection mold and the core of the extrusion mold both adopted hardened material H13 (HRC48-52).

Lamp production technology points:

Size: the light tube is an integrated design with complex structures. Meanwhile, the light tube needs to be assembled with side cover, LED light strips, clips, therefore, the size of it becomes the most important factor in production. If the size is too small, the side cover will get loose and cannot be fixed, and the LED strip inside cannot be inserted easily, too. If the size is too large,the LED strip will get loose and the light source will be biased towards one side. The size is directly related to the temperature and speed of extrusion. After multiple testings, we found that the size meets the assembly standards when the speed is 1.15 meters per minute.

Transparency: Transmittance and haze are inversely proportional, which means that not only we need to ensure the good transmittance of the lamp tube but also good haze of the product. In order to avoid direct visibility of the lamp beads inside the lamp tube, we had a discussion with the client and tested 5 different transparency samples overnight under a 4000K light strip, including the transparent tube (tube A) that the Italian client prefers. From the photos, it can be seen that when the ratio of diffusion powder is 1:4, the brightness and uniformity of the light does improve, and the internal light beads (tube E) can be seen clearly. When the ratio is 1:8 (tube B), the lighting effect was significantly improved, and the haze and transmittance met the standards, too. The light source is uniform and soft, and the light beads can also be covered well.

According to the feedback from the market, customers prefer light tube B. We conducted temperature and color testing on light tube B immediately and the result showed that is 4107K.

To meet different customer’s needs, we slightly adjusted type A and type C light tubes with different transparency based on light tube B to find out the feedback of the different temperature color in the market.

Inspection: We have developed detailed assembly tests for the light tubes in the production process, which required all accessory assembly tests to be conducted twice per hour. We have made LED light strips at the production site to test the light transmittance of each light tube, and time marked and classified the samples hourly.

Packaging: We adopted integrated extrusion film sticking equipment to apply a low adhesive film on the front of the lamp tube while extruding, as to avoid scratches on the front of the lamp tube. The packaging method uses 10 lamp tubes as a set, and each set of light tubes is comprehensively inspected on site by LED light strips so that no black spots or other defects arise. Moreover, the qualified products are bundled in bundles of 60 tubes and wrapped in bubble-wrap. The outer box is made of 7-layer cardboard boxes, and the four corners are fixed with clips and straps.

Service of GREFEE:

GREFEE works 24 hours a day and we are motivated to help our customers with producing the products they want. From ideas to reality, we have comprehensive production line and professional extrusion project engineers. Also, we are equipped with different types of extrusion machines. If you wanna ask any extrusion questions, please contact us. Our engineering team provides free design and product advice.

Of course, for lighting products, our manufacturing and production capabilities are far more than just light profile. We have also made lighting products for many other industries, such as lifestyle products. We have made beauty lighting lamps for hotels. This product uses a lot of processes, including injection molding, die-casting, stamping, CNC processing, and post-processing includes spraying, chrome plating, galvanizing and other processes (if you are interested, you can click the link); in the automotive industry, we have made all the plastic accessories of the headlight group, including LED light strips, headlight bodies, headlight shells and glass lenses (optical molds)