In devices such as smartwatches,IoT sensors,or wireless earphones,BLE(Bluetooth Low Energy)modules serve as the"nerve center"connecting the world.Users expect these devices to be thin,portable,and low-power,while also functioning reliably in various scenarios like rainy days,swimming pools,or outdoor environments.This means that the shells of BLE modules must meet the seemingly contradictory requirements of being"less than 1mm thick"and"IP67-level dust and water-resistant".How can this challenge be addressed?Precision CNC machining technology provides the solution.
I.Why Do BLE Modules Need"Lightweight+Protection"?
The core advantage of BLE devices is"low power consumption,"and the weight of the shell directly affects battery life:reducing the weight by just 1 gram can free up more space for the battery or make the device more wearable.However,"thin and light"often means a reduction in the structural strength of the shell,making it unable to withstand water or dust ingress.The IP67 standard requires that devices can withstand immersion in water up to 1 meter deep for 30 minutes without damage,while also completely preventing dust entry.This poses extremely high demands on the sealing performance of thin-walled shells.
Traditional injection-molded shells,while lightweight,cannot achieve the dimensional tolerances required for precision parts(e.g.,±0.01mm).Rough sealing grooves can prevent the sealing rings from fitting perfectly.On the other hand,heavy metal shells,although meeting protection requirements,go against the lightweight nature of BLE modules.At this point,CNC turning and milling of precision metal parts becomes the key to balancing these two aspects.
II.How Does Precision CNC Achieve"Lightweight+Protection"?
To meet the requirements of being both"light"and"protected,"the approach must be threefold:material selection,machining process,and sealing design.The high precision and flexibility of CNC machining cover all these aspects.
1.Material:Choosing the Right"Light and Strong"Metal
To achieve lightweighting,we typically select aluminum alloy 6061-T6 or titanium alloy TC4.The former has a density of only 2.7g/cm³(about 1/3 that of steel)and can reach a strength of 420MPa after heat treatment.The latter,with a density of 4.5g/cm³ and a higher strength of about 900MPa,is suitable for more extreme outdoor scenarios.These materials are not only lightweight but also corrosion-resistant,capable of withstanding humid environments without additional coating.
However,being"light"is just the foundation.How do we process these metals into shells with a wall thickness of less than 1mm?This requires the high rigidity and high-speed cutting capabilities of CNC machines.For example,using a 2mm diameter tungsten carbide end mill at a speed of 10,000rpm for side milling allows for precise removal of excess metal without causing deformation,preserving the strength of the thin-walled structure.
2.Process:CNC Turning and Milling to Solve the"Deformation"Challenge
The difficulty in machining thin-walled parts lies in their susceptibility to deformation.When the cutting tool exerts force,the material can warp due to stress release,leading to dimensional errors exceeding the allowable range(e.g.,±0.01mm).To address this,we employ CNC turning and milling composite processing technology:
• First,the metal rod is turned on a lathe to form the basic shape of the shell(e.g.,cylindrical or rectangular),ensuring the flatness of the reference surface.
• Then,a milling machine is used to process details such as sealing grooves and mounting holes.The four-axis function of the machine ensures that the cutting tool moves along the curved surface trajectory of the shell,avoiding excessive localized force.
• Finally,stress-relief annealing is applied to eliminate internal stresses generated during machining,ensuring that the shell does not deform during subsequent assembly.
Through this process,we can control the dimensional error of the thin-walled shell to within±0.005mm,far exceeding the±0.02mm requirement for IP67 sealing.
3.Sealing:"Micron-Level Grooves"from CNC Machining for Reliable Water Resistance
The core of IP67 protection is the sealing structure,and the effectiveness of the sealing ring depends on the dimensional accuracy and surface roughness of the groove.Traditional injection-molded grooves have a surface roughness of about Ra1.6μm,which cannot fully conform to the sealing ring.In contrast,CNC-machined grooves achieve a surface roughness of less than Ra0.8μm,with dimensional errors of only±0.01mm,allowing the sealing ring(e.g.,nitrile rubber or silicone rubber)to fully fill the groove and create a"zero-gap"seal.
For example,we designed a shell for a BLE sensor manufacturer with a sealing groove width of 2.0mm and depth of 1.5mm,machined by a CNC milling machine at a feed rate of 1000mm/min.Tests showed that after 24 hours of immersion in 1 meter of water,the internal humidity of the shell remained below 5%,fully meeting the IP67 requirement.
III.Case Study:Lightweight+Protection Solution for a Smartwatch BLE Module
A well-known smartwatch manufacturer needed to design a shell for its new BLE module with the following requirements:weight≤5g(a 30%reduction from the previous generation),IP67-level protection,and wall thickness≤1.2mm.We achieved this goal through the following steps:
• Material Selection:We chose aluminum alloy 6061-T6,with a density of 2.7g/cm³,60%lighter than the stainless steel shell of the previous generation.
• Process Design:Using a CNC turning and milling machine,we first turned the material into a cylinder with a diameter of 20mm and a height of 8mm,then milled it to a thin-walled structure with a thickness of 1.0mm.
• Sealing Treatment:We machined a sealing groove with a width of 2.0mm and a depth of 1.5mm at the bottom of the shell,which,combined with a silicone rubber sealing ring,achieved IP67 protection.
• Weight Optimization:Using topology optimization software,we removed unnecessary material from the interior of the shell,further reducing the weight to 4.8g.
Ultimately,the battery life of the BLE module increased by 25%compared to the previous generation(due to the reduced weight and unchanged battery capacity,power consumption decreased),and it could be used normally while swimming,earning high recognition from the manufacturer.
IV.Conclusion:Precision CNC as the"Invisible Guardian"of BLE Modules
For BLE devices,"lightweight"is the core of user experience,while"protection"is the foundation of reliability.Precision CNC machining technology,with its high accuracy and flexibility,resolves the contradiction between"thin and strong"and"light and protected,"enabling BLE modules to function in more scenarios—from smartwatches to industrial sensors,and from outdoor adventures to daily use.
If you are struggling with the shell design for your BLE module,consider CNC turning and milling of precision metal parts.It can not only help you achieve lightweighting but also make your device more durable and reliable.After all,a good product should not only"look good"but also"work well."