In defense manufacturing, repeatability and complete control over every stage of production are crucial. From the quality of CNC machining and surface preparation to final assembly, each step must be performed with consistent precision to ensure that the finished component fully meets the design requirements.
One of the final stages is mechanical assembly, in which precisely machined parts form a complete assembly. It is at this point that the experience of the employees, good work organization, and effective quality control determine the final result.
In the rest of this article, we show you what the mechanical assembly process looks like, which we have perfected at SIM Gdynia over more than 45 years of operation – from the preparation of details to the final verification of the finished component.
Table of contents
From design to assembly – how the process works
The process begins with an order for a complete assembly, in which each element is designed for a precise fit. The subassemblies are manufactured on our CNC machining centers – lathes, 4- and 5-axis milling machines, depending on the geometry and required tolerances.
For components intended for defense applications, it is crucial to maintain dimensions and surface cleanliness, as they often operate in environments with increased requirements for tightness, vibration resistance, or heat resistance. Therefore, each stage of processing is carefully monitored and documented.
After machining, the parts are sent to the metalworking department, where they are cleaned, deburred, and pre-verified. At this stage, burrs, sharp edges, and cooling emulsion residues are removed. Each part undergoes a visual inspection before moving on to the next stages of the process.
Some components, especially those used in military systems, are then sent to external partners for blackening, anodizing, galvanizing, or other surface protection processes. Such coatings increase corrosion resistance and improve conductivity properties. After returning from finishing, the parts are recorded and sent for final assembly.
Step–by–step mechanical assembly
Each assembly has a designated person in charge – a technician who oversees the process from the moment the parts are received to the final quality control. This person supervises compliance with documentation, the sequence of operations, and the final result.
Verification and preparation
Before the actual assembly begins, all parts are thoroughly checked for dimensions, cleanliness, and completeness. The inspection is carried out in the presence of a quality control employee, who confirms that all details meet the drawing and surface requirements. At this stage, the assembler also prepares the necessary tools, torque wrenches, safety measures, and compiles a set of components for a given assembly.
In the case of projects for the defense sector, particular attention is paid to the cleanliness of the assembly and the maintenance of connection parameters – even slight contamination or incorrect tightening can affect the operation of the system in the field.
Assembling and securing connections
Assembly is like a precise jigsaw puzzle, in which each component has its place and orientation. The fit requires accuracy down to hundredths and thousandths of a millimeter. Screw connections are tightened to a specified torque, and in places requiring a permanent bond, assembly adhesives or thread locks are used.
In military designs, spacers, retaining sleeves, or threaded inserts are often used to increase the durability of connections in hard materials. Such solutions allow for trouble-free operation even under high dynamic loads. The installer’s task is not only to assemble the parts, but also to ensure that the entire assembly works smoothly, without play or jamming.
The process involves quality control, which verifies the compliance of each step with the technical documentation. Each assembled element is checked for dimensions, tightening torques, and overall appearance—no part may show signs of impact or scratches.
Work organization and interdepartmental cooperation
Depending on the complexity of the project, the assembler works with metalworkers who help prepare components or larger structures.
Assembly teams remain flexible—their composition may change depending on the current production load.
The entire process requires close interdepartmental coordination. CNC production is responsible for the accuracy of the components, the metalworking shop for their preparation, cooperation for the quality of the coatings, and assembly for the final fit and completeness. All activities are recorded in the system, which ensures full traceability of each element – from the material to the finished assembly.
Securing and shipping finished components
After assembly, each assembly is cleaned and properly secured. The components are placed in special compartments or technical foams that protect them from dents and scratches during transport. Then, the complete sets are packed, labeled, and transferred to the warehouse or directly to shipping, depending on the arrangements with the customer.
Finally, the assembler and quality control prepare inspection documentation confirming dimensional compliance, assembly quality, and surface condition. In the case of projects for the defense sector, this document forms the basis for issuing a quality certificate, which is necessary for deliveries to military systems.
Summary
Mechanical assembly is not only the final stage of production, but a process that requires precision, cleanliness, and responsibility at every level. From dimensional control to final packaging, every step matters.
At SIM Gdynia, assembly is carried out by dedicated personnel who are responsible for the entire process and cooperate with the locksmith and quality control departments. This approach allows us to maintain the highest standards required in defense industry projects and ensure that the finished components reach customers in full compliance with the documentation—ready to work in systems where reliability is as important as precision.